add ode

1 files changed, 1380 insertions, 0 deletions

diff --git a/libs/ode-0.16.1/ode/demo/demo_ode.cpp b/libs/ode-0.16.1/ode/demo/demo_ode.cpp
new file mode 100644
index 0000000..ead9338
--- /dev/null
+++ b/libs/ode-0.16.1/ode/demo/demo_ode.cpp
@@ -0,0 +1,1380 @@
+/*************************************************************************
+ *                                                                       *
+ * Open Dynamics Engine, Copyright (C) 2001,2002 Russell L. Smith.       *
+ * All rights reserved.  Email: russ@q12.org   Web: www.q12.org          *
+ *                                                                       *
+ * This library is free software; you can redistribute it and/or         *
+ * modify it under the terms of EITHER:                                  *
+ *   (1) The GNU Lesser General Public License as published by the Free  *
+ *       Software Foundation; either version 2.1 of the License, or (at  *
+ *       your option) any later version. The text of the GNU Lesser      *
+ *       General Public License is included with this library in the     *
+ *       file LICENSE.TXT.                                               *
+ *   (2) The BSD-style license that is included with this library in     *
+ *       the file LICENSE-BSD.TXT.                                       *
+ *                                                                       *
+ * This library is distributed in the hope that it will be useful,       *
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of        *
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the files    *
+ * LICENSE.TXT and LICENSE-BSD.TXT for more details.                     *
+ *                                                                       *
+ *************************************************************************/
+
+#include <setjmp.h>
+#include <ode/ode.h>
+
+#ifdef _MSC_VER
+#pragma warning(disable:4244 4305)  // for VC++, no precision loss complaints
+#endif
+
+//****************************************************************************
+// matrix sizes
+
+#define dALIGN_SIZE(buf_size, alignment) (((buf_size) + (alignment - 1)) & (int)(~(alignment - 1))) // Casting the mask to int ensures sign-extension to larger integer sizes
+#define dALIGN_PTR(buf_ptr, alignment) ((void *)(((duintptr)(buf_ptr) + ((alignment) - 1)) & (int)(~(alignment - 1)))) // Casting the mask to int ensures sign-extension to larger integer sizes
+
+#define MSIZE 21
+#define MSIZE4 dALIGN_SIZE(MSIZE, 4)	// MSIZE rounded up to 4
+
+
+
+//****************************************************************************
+// matrix accessors
+
+#define _A(i,j) A[(i)*4+(j)]
+#define _I(i,j) I[(i)*4+(j)]
+#define _R(i,j) R[(i)*4+(j)]
+
+//****************************************************************************
+// tolerances
+
+#ifdef dDOUBLE
+const double tol = 1e-10;
+#endif
+
+#ifdef dSINGLE
+const double tol = 1e-5;
+#endif
+
+//****************************************************************************
+// misc messages and error handling
+
+#ifdef __GNUC__
+#define HEADER printf ("%s()\n", __FUNCTION__);
+#else
+#define HEADER printf ("%s:%d\n",__FILE__,__LINE__);
+#endif
+
+static jmp_buf jump_buffer;
+
+
+void myMessageFunction (int num, const char *msg, va_list ap)
+{
+    printf ("(Message %d: ",num);
+    vprintf (msg,ap);
+    printf (")");
+    dSetMessageHandler (0);
+    longjmp (jump_buffer,1);
+}
+
+
+#define TRAP_MESSAGE(do,ifnomsg,ifmsg) \
+    dSetMessageHandler (&myMessageFunction); \
+    if (setjmp (jump_buffer)) { \
+        dSetMessageHandler (0); \
+        ifmsg ; \
+    } \
+    else { \
+        dSetMessageHandler (&myMessageFunction); \
+        do ; \
+        ifnomsg ; \
+    } \
+    dSetMessageHandler (0);
+
+//****************************************************************************
+// utility stuff
+
+// compare two numbers, within a threshhold, return 1 if approx equal
+
+int cmp (dReal a, dReal b)
+{
+    return (fabs(a-b) < tol);
+}
+
+//****************************************************************************
+// matrix utility stuff
+
+// compare a 3x3 matrix with the identity
+
+int cmpIdentityMat3 (dMatrix3 A)
+{
+    return
+        (cmp(_A(0,0),1.0) && cmp(_A(0,1),0.0) && cmp(_A(0,2),0.0) &&
+        cmp(_A(1,0),0.0) && cmp(_A(1,1),1.0) && cmp(_A(1,2),0.0) &&
+        cmp(_A(2,0),0.0) && cmp(_A(2,1),0.0) && cmp(_A(2,2),1.0));
+}
+
+
+// transpose a 3x3 matrix in-line
+
+void transpose3x3 (dMatrix3 A)
+{
+    dReal tmp;
+    tmp=A[4]; A[4]=A[1]; A[1]=tmp;
+    tmp=A[8]; A[8]=A[2]; A[2]=tmp;
+    tmp=A[9]; A[9]=A[6]; A[6]=tmp;
+}
+
+//****************************************************************************
+// test miscellaneous math functions
+
+void testRandomNumberGenerator()
+{
+    HEADER;
+    if (dTestRand()) printf ("\tpassed\n");
+    else printf ("\tFAILED\n");
+}
+
+
+void testInfinity()
+{
+    HEADER;
+    if (1e10 < dInfinity && -1e10 > -dInfinity && -dInfinity < dInfinity)
+        printf ("\tpassed\n");
+    else printf ("\tFAILED\n");
+}
+
+
+void testPad()
+{
+    HEADER;
+    char s[100];
+    s[0]=0;
+    for (int i=0; i<=16; i++) sprintf (s+strlen(s),"%d ",dPAD(i));
+    printf ("\t%s\n", strcmp(s,"0 1 4 4 4 8 8 8 8 12 12 12 12 16 16 16 16 ") ?
+        "FAILED" : "passed");
+}
+
+
+void testCrossProduct()
+{
+    HEADER;
+
+    dVector3 a1,a2,b,c;
+    dMatrix3 B;
+    dMakeRandomVector (b,3,1.0);
+    dMakeRandomVector (c,3,1.0);
+
+    dCalcVectorCross3(a1,b,c);
+
+    dSetZero (B,12);
+    dSetCrossMatrixPlus(B,b,4);
+    dMultiply0 (a2,B,c,3,3,1);
+
+    dReal diff = dMaxDifference(a1,a2,3,1);
+    printf ("\t%s\n", diff > tol ? "FAILED" : "passed");
+}
+
+
+void testSetZero()
+{
+    HEADER;
+    dReal a[100];
+    dMakeRandomVector (a,100,1.0);
+    dSetZero (a,100);
+    for (int i=0; i<100; i++) if (a[i] != 0.0) {
+        printf ("\tFAILED\n");
+        return;
+    }
+    printf ("\tpassed\n");
+}
+
+
+void testNormalize3()
+{
+    HEADER;
+    int i,j,bad=0;
+    dVector3 n1,n2;
+    for (i=0; i<1000; i++) {
+        dMakeRandomVector (n1,3,1.0);
+        for (j=0; j<3; j++) n2[j]=n1[j];
+        dNormalize3 (n2);
+        if (dFabs(dCalcVectorDot3(n2,n2) - 1.0) > tol) bad |= 1;
+        if (dFabs(n2[0]/n1[0] - n2[1]/n1[1]) > tol) bad |= 2;
+        if (dFabs(n2[0]/n1[0] - n2[2]/n1[2]) > tol) bad |= 4;
+        if (dFabs(n2[1]/n1[1] - n2[2]/n1[2]) > tol) bad |= 8;
+        if (dFabs(dCalcVectorDot3(n2,n1) - dSqrt(dCalcVectorDot3(n1,n1))) > tol) bad |= 16;
+        if (bad) {
+            printf ("\tFAILED (code=%x)\n",bad);
+            return;
+        }
+    }
+    printf ("\tpassed\n");
+}
+
+
+/*
+void testReorthonormalize()
+{
+HEADER;
+dMatrix3 R,I;
+dMakeRandomMatrix (R,3,3,1.0);
+for (int i=0; i<30; i++) dReorthonormalize (R);
+dMultiply2 (I,R,R,3,3,3);
+printf ("\t%s\n",cmpIdentityMat3 (I) ? "passed" : "FAILED");
+}
+*/
+
+
+void testPlaneSpace()
+{
+    HEADER;
+    dVector3 n,p,q;
+    int bad = 0;
+    for (int i=0; i<1000; i++) {
+        dMakeRandomVector (n,3,1.0);
+        dNormalize3 (n);
+        dPlaneSpace (n,p,q);
+        if (fabs(dCalcVectorDot3(n,p)) > tol) bad = 1;
+        if (fabs(dCalcVectorDot3(n,q)) > tol) bad = 1;
+        if (fabs(dCalcVectorDot3(p,q)) > tol) bad = 1;
+        if (fabs(dCalcVectorDot3(p,p)-1) > tol) bad = 1;
+        if (fabs(dCalcVectorDot3(q,q)-1) > tol) bad = 1;
+    }
+    printf ("\t%s\n", bad ? "FAILED" : "passed");
+}
+
+//****************************************************************************
+// test matrix functions
+
+void testMatrixMultiply()
+{
+    // A is 2x3, B is 3x4, B2 is B except stored columnwise, C is 2x4
+    dReal A[8],B[12],A2[12],B2[16],C[8];
+    int i;
+
+    HEADER;
+    dSetZero (A,8);
+    for (i=0; i<3; i++) A[i] = i+2;
+    for (i=0; i<3; i++) A[i+4] = i+3+2;
+    for (i=0; i<12; i++) B[i] = i+8;
+    dSetZero (A2,12);
+    for (i=0; i<6; i++) A2[i+2*(i/2)] = A[i+i/3];
+    dSetZero (B2,16);
+    for (i=0; i<12; i++) B2[i+i/3] = B[i];
+
+    dMultiply0 (C,A,B,2,3,4);
+    if (C[0] != 116 || C[1] != 125 || C[2] != 134 || C[3] != 143 ||
+        C[4] != 224 || C[5] != 242 || C[6] != 260 || C[7] != 278)
+        printf ("\tFAILED (1)\n"); else printf ("\tpassed (1)\n");
+
+    dMultiply1 (C,A2,B,2,3,4);
+    if (C[0] != 160 || C[1] != 172 || C[2] != 184 || C[3] != 196 ||
+        C[4] != 196 || C[5] != 211 || C[6] != 226 || C[7] != 241)
+        printf ("\tFAILED (2)\n"); else printf ("\tpassed (2)\n");
+
+    dMultiply2 (C,A,B2,2,3,4);
+    if (C[0] != 83 || C[1] != 110 || C[2] != 137 || C[3] != 164 ||
+        C[4] != 164 || C[5] != 218 || C[6] != 272 || C[7] != 326)
+        printf ("\tFAILED (3)\n"); else printf ("\tpassed (3)\n");
+}
+
+
+void testSmallMatrixMultiply()
+{
+    dMatrix3 A,B,C,A2;
+    dVector3 a,a2,x;
+
+    HEADER;
+    dMakeRandomMatrix (A,3,3,1.0);
+    dMakeRandomMatrix (B,3,3,1.0);
+    dMakeRandomMatrix (C,3,3,1.0);
+    dMakeRandomMatrix (x,3,1,1.0);
+
+    // dMultiply0_331()
+    dMultiply0_331 (a,B,x);
+    dMultiply0 (a2,B,x,3,3,1);
+    printf ("\t%s (1)\n",(dMaxDifference (a,a2,3,1) > tol) ? "FAILED" :
+        "passed");
+
+    // dMultiply1_331()
+    dMultiply1_331 (a,B,x);
+    dMultiply1 (a2,B,x,3,3,1);
+    printf ("\t%s (2)\n",(dMaxDifference (a,a2,3,1) > tol) ? "FAILED" :
+        "passed");
+
+    // dMultiply0_133
+    dMultiply0_133 (a,x,B);
+    dMultiply0 (a2,x,B,1,3,3);
+    printf ("\t%s (3)\n",(dMaxDifference (a,a2,1,3) > tol) ? "FAILED" :
+        "passed");
+
+    // dMultiply0_333()
+    dMultiply0_333 (A,B,C);
+    dMultiply0 (A2,B,C,3,3,3);
+    printf ("\t%s (4)\n",(dMaxDifference (A,A2,3,3) > tol) ? "FAILED" :
+        "passed");
+
+    // dMultiply1_333()
+    dMultiply1_333 (A,B,C);
+    dMultiply1 (A2,B,C,3,3,3);
+    printf ("\t%s (5)\n",(dMaxDifference (A,A2,3,3) > tol) ? "FAILED" :
+        "passed");
+
+    // dMultiply2_333()
+    dMultiply2_333 (A,B,C);
+    dMultiply2 (A2,B,C,3,3,3);
+    printf ("\t%s (6)\n",(dMaxDifference (A,A2,3,3) > tol) ? "FAILED" :
+        "passed");
+}
+
+
+void testCholeskyFactorization()
+{
+    dsizeint matrixSize = sizeof(dReal) * MSIZE4 * MSIZE;
+    dReal *A = (dReal *)dAlloc(matrixSize), *B = (dReal *)dAlloc(matrixSize), *C = (dReal *)dAlloc(matrixSize), diff;
+
+    HEADER;
+    dMakeRandomMatrix (A,MSIZE,MSIZE,1.0);
+    dMultiply2 (B,A,A,MSIZE,MSIZE,MSIZE);
+    memcpy (A,B,MSIZE4*MSIZE*sizeof(dReal));
+    if (dFactorCholesky (B,MSIZE)) printf ("\tpassed (1)\n");
+    else printf ("\tFAILED (1)\n");
+    dClearUpperTriangle (B,MSIZE);
+    dMultiply2 (C,B,B,MSIZE,MSIZE,MSIZE);
+    diff = dMaxDifference(A,C,MSIZE,MSIZE);
+    printf ("\tmaximum difference = %.6e - %s (2)\n",diff,
+        diff > tol ? "FAILED" : "passed");
+
+    dFree(C, matrixSize);
+    dFree(B, matrixSize);
+    dFree(A, matrixSize);
+}
+
+
+void testCholeskySolve()
+{
+    dsizeint matrixSize = sizeof(dReal) * MSIZE4 * MSIZE, vectorSize = sizeof(dReal) * MSIZE;
+    dReal *A = (dReal *)dAlloc(matrixSize), *L = (dReal *)dAlloc(matrixSize);
+    dReal *b = (dReal *)dAlloc(vectorSize), *x = (dReal *)dAlloc(vectorSize), *btest = (dReal *)dAlloc(vectorSize), diff;
+
+    HEADER;
+
+    // get A,L = PD matrix
+    dMakeRandomMatrix (A,MSIZE,MSIZE,1.0);
+    dMultiply2 (L,A,A,MSIZE,MSIZE,MSIZE);
+    memcpy (A,L,MSIZE4*MSIZE*sizeof(dReal));
+
+    // get b,x = right hand side
+    dMakeRandomMatrix (b,MSIZE,1,1.0);
+    memcpy (x,b,MSIZE*sizeof(dReal));
+
+    // factor L
+    if (dFactorCholesky (L,MSIZE)) printf ("\tpassed (1)\n");
+    else printf ("\tFAILED (1)\n");
+    dClearUpperTriangle (L,MSIZE);
+
+    // solve A*x = b
+    dSolveCholesky (L,x,MSIZE);
+
+    // compute A*x and compare it with b
+    dMultiply2 (btest,A,x,MSIZE,MSIZE,1);
+    diff = dMaxDifference(b,btest,MSIZE,1);
+    printf ("\tmaximum difference = %.6e - %s (2)\n",diff,
+        diff > tol ? "FAILED" : "passed");
+
+    dFree(btest, vectorSize);
+    dFree(x, vectorSize);
+    dFree(b, vectorSize);
+    dFree(L, matrixSize);
+    dFree(A, matrixSize);
+}
+
+
+void testInvertPDMatrix()
+{
+    int i,j,ok;
+    dsizeint matrixSize = sizeof(dReal) * MSIZE4 * MSIZE;
+    dReal *A = (dReal *)dAlloc(matrixSize), *Ainv = (dReal *)dAlloc(matrixSize), *I = (dReal *)dAlloc(matrixSize);
+
+    HEADER;
+
+    dMakeRandomMatrix (A,MSIZE,MSIZE,1.0);
+    dMultiply2 (Ainv,A,A,MSIZE,MSIZE,MSIZE);
+    memcpy (A,Ainv,MSIZE4*MSIZE*sizeof(dReal));
+    dSetZero (Ainv,MSIZE4*MSIZE);
+
+    if (dInvertPDMatrix (A,Ainv,MSIZE))
+        printf ("\tpassed (1)\n"); else printf ("\tFAILED (1)\n");
+    dMultiply0 (I,A,Ainv,MSIZE,MSIZE,MSIZE);
+
+    // compare with identity
+    ok = 1;
+    for (i=0; i<MSIZE; i++) {
+        for (j=0; j<MSIZE; j++) {
+            if (i != j) if (cmp (I[i*MSIZE4+j],0.0)==0) ok = 0;
+        }
+    }
+    for (i=0; i<MSIZE; i++) {
+        if (cmp (I[i*MSIZE4+i],1.0)==0) ok = 0;
+    }
+    if (ok) printf ("\tpassed (2)\n"); else printf ("\tFAILED (2)\n");
+
+    dFree(I, matrixSize);
+    dFree(Ainv, matrixSize);
+    dFree(A, matrixSize);
+}
+
+
+void testIsPositiveDefinite()
+{
+    dsizeint matrixSize = sizeof(dReal) * MSIZE4 * MSIZE;
+    dReal *A = (dReal *)dAlloc(matrixSize), *B = (dReal *)dAlloc(matrixSize);
+
+    HEADER;
+
+    dMakeRandomMatrix (A,MSIZE,MSIZE,1.0);
+    dMultiply2 (B,A,A,MSIZE,MSIZE,MSIZE);
+    printf ("\t%s\n",dIsPositiveDefinite(A,MSIZE) ? "FAILED (1)":"passed (1)");
+    printf ("\t%s\n",dIsPositiveDefinite(B,MSIZE) ? "passed (2)":"FAILED (2)");
+
+    dFree(B, matrixSize);
+    dFree(A, matrixSize);
+}
+
+
+void testFastLDLTFactorization()
+{
+    int i,j;
+    dsizeint matrixSize = sizeof(dReal) * MSIZE4 * MSIZE, vectorSize = sizeof(dReal) * MSIZE;
+    dReal *A = (dReal *)dAlloc(matrixSize), *L = (dReal *)dAlloc(matrixSize), *DL = (dReal *)dAlloc(matrixSize),
+        *ATEST = (dReal *)dAlloc(matrixSize), *d = (dReal *)dAlloc(vectorSize), diff;
+
+    HEADER;
+
+    dMakeRandomMatrix (A,MSIZE,MSIZE,1.0);
+    dMultiply2 (L,A,A,MSIZE,MSIZE,MSIZE);
+    memcpy (A,L,MSIZE4*MSIZE*sizeof(dReal));
+
+    dFactorLDLT (L,d,MSIZE,MSIZE4);
+
+    dClearUpperTriangle (L,MSIZE);
+    for (i=0; i<MSIZE; i++) L[i*MSIZE4+i] = 1.0;
+
+    dSetZero (DL,MSIZE4*MSIZE);
+    for (i=0; i<MSIZE; i++) {
+        for (j=0; j<MSIZE; j++) DL[i*MSIZE4+j] = L[i*MSIZE4+j] / d[j];
+    }
+
+    dMultiply2 (ATEST,L,DL,MSIZE,MSIZE,MSIZE);
+    diff = dMaxDifference(A,ATEST,MSIZE,MSIZE);
+    printf ("\tmaximum difference = %.6e - %s\n",diff,
+        diff > tol ? "FAILED" : "passed");
+
+    dFree(d, vectorSize);
+    dFree(ATEST, matrixSize);
+    dFree(DL, matrixSize);
+    dFree(L, matrixSize);
+    dFree(A, matrixSize);
+}
+
+
+void testCoopLDLTFactorization()
+{
+    int i,j;
+
+    const dsizeint COOP_MSIZE = MSIZE * 51, COOP_MSIZE4 = dALIGN_SIZE(COOP_MSIZE, 4);
+
+    dsizeint matrixSize = sizeof(dReal) * COOP_MSIZE4 * COOP_MSIZE, vectorSize = sizeof(dReal) * COOP_MSIZE;
+    dReal *A = (dReal *)dAlloc(matrixSize), *L = (dReal *)dAlloc(matrixSize), *DL = (dReal *)dAlloc(matrixSize),
+        *ATEST = (dReal *)dAlloc(matrixSize), *d = (dReal *)dAlloc(vectorSize), diff;
+
+    const unsigned threadCountMaximum = 8;
+    dThreadingImplementationID threading = dThreadingAllocateMultiThreadedImplementation();
+    dCooperativeID cooperative = dCooperativeCreate(dThreadingImplementationGetFunctions(threading), threading);
+    dThreadingThreadPoolID pool = dThreadingAllocateThreadPool(threadCountMaximum, 0, dAllocateFlagBasicData, NULL);
+    dThreadingThreadPoolServeMultiThreadedImplementation(pool, threading);
+
+    dResourceRequirementsID requirements = dResourceRequirementsCreate(cooperative);
+    dEstimateCooperativelyFactorLDLTResourceRequirements(requirements, threadCountMaximum, COOP_MSIZE);
+    dResourceContainerID resources = dResourceContainerAcquire(requirements);
+
+    HEADER;
+
+    for (int pass = 0; pass != 4; ++pass)
+    {
+        dTimerStart ("Factoring LDLT");
+
+        const unsigned allowedThreads = 4;
+        const unsigned PASS_MSIZE = COOP_MSIZE - pass, PASS_MSIZE4 = dALIGN_SIZE(PASS_MSIZE, 4);
+
+        dTimerNow ("Preparing data");
+        dMakeRandomMatrix (L, PASS_MSIZE, PASS_MSIZE, 1.0);
+        dMultiply2 (A, L, L, PASS_MSIZE, PASS_MSIZE, PASS_MSIZE);
+        memcpy (L, A, sizeof(dReal) * PASS_MSIZE4 * PASS_MSIZE);
+
+        dTimerNow ("Factoring multi threaded");
+        dCooperativelyFactorLDLT (resources, allowedThreads, L, d, PASS_MSIZE, PASS_MSIZE4);
+
+        dTimerNow ("Verifying");
+        dClearUpperTriangle (L, PASS_MSIZE);
+        for (i = 0; i < PASS_MSIZE; i++) L[i * PASS_MSIZE4 + i] = 1.0;
+
+        dSetZero (DL, PASS_MSIZE4 * PASS_MSIZE);
+        for (i = 0; i < PASS_MSIZE; i++) {
+            for (j = 0; j < PASS_MSIZE; j++) DL[i * PASS_MSIZE4 + j] = L[i * PASS_MSIZE4 + j] / d[j];
+        }
+
+        dMultiply2 (ATEST, L, DL, PASS_MSIZE, PASS_MSIZE, PASS_MSIZE);
+        diff = dMaxDifference(A, ATEST, PASS_MSIZE, PASS_MSIZE);
+        printf ("\tN=%u: maximum difference = %.6e - %s\n", PASS_MSIZE, diff, diff > 1e2 * tol ? "FAILED" : "passed");
+
+        dTimerEnd();
+        dTimerReport(stdout, 0);
+    }
+
+    dResourceContainerDestroy(resources);
+    dResourceRequirementsDestroy(requirements);
+
+    dThreadingImplementationShutdownProcessing(threading);
+    dThreadingFreeThreadPool(pool);
+    dCooperativeDestroy(cooperative);
+    dThreadingFreeImplementation(threading);
+
+    dFree(d, vectorSize);
+    dFree(ATEST, matrixSize);
+    dFree(DL, matrixSize);
+    dFree(L, matrixSize);
+    dFree(A, matrixSize);
+}
+
+
+void testSolveLDLT()
+{
+    dsizeint matrixSize = sizeof(dReal) * MSIZE4 * MSIZE, vectorSize = sizeof(dReal) * MSIZE;
+    dReal *A = (dReal *)dAlloc(matrixSize), *L = (dReal *)dAlloc(matrixSize), 
+        *d = (dReal *)dAlloc(vectorSize), *x = (dReal *)dAlloc(vectorSize), 
+        *b = (dReal *)dAlloc(vectorSize), *btest = (dReal *)dAlloc(vectorSize), diff;
+
+    HEADER;
+
+    dMakeRandomMatrix (A,MSIZE,MSIZE,1.0);
+    dMultiply2 (L,A,A,MSIZE,MSIZE,MSIZE);
+    memcpy (A,L,MSIZE4*MSIZE*sizeof(dReal));
+
+    dMakeRandomMatrix (b,MSIZE,1,1.0);
+    memcpy (x,b,MSIZE*sizeof(dReal));
+
+    dFactorLDLT (L,d,MSIZE,MSIZE4);
+    dSolveLDLT (L,d,x,MSIZE,MSIZE4);
+
+    dMultiply2 (btest,A,x,MSIZE,MSIZE,1);
+    diff = dMaxDifference(b,btest,MSIZE,1);
+    printf ("\tmaximum difference = %.6e - %s\n",diff,
+        diff > tol ? "FAILED" : "passed");
+
+    dFree(btest, vectorSize);
+    dFree(b, vectorSize);
+    dFree(x, vectorSize);
+    dFree(d, vectorSize);
+    dFree(L, matrixSize);
+    dFree(A, matrixSize);
+}
+
+void testCoopSolveLDLT()
+{
+    const dsizeint COOP_MSIZE = MSIZE * 51, COOP_MSIZE4 = dALIGN_SIZE(COOP_MSIZE, 4);
+
+    dsizeint matrixSize = sizeof(dReal) * COOP_MSIZE4 * COOP_MSIZE, vectorSize = sizeof(dReal) * COOP_MSIZE;
+    dReal *A = (dReal *)dAlloc(matrixSize), *L = (dReal *)dAlloc(matrixSize), 
+        *d = (dReal *)dAlloc(vectorSize), *x = (dReal *)dAlloc(vectorSize), 
+        *b = (dReal *)dAlloc(vectorSize), *btest = (dReal *)dAlloc(vectorSize), diff;
+
+    const unsigned threadCountMaximum = 8;
+    dThreadingImplementationID threading = dThreadingAllocateMultiThreadedImplementation();
+    dCooperativeID cooperative = dCooperativeCreate(dThreadingImplementationGetFunctions(threading), threading);
+    dThreadingThreadPoolID pool = dThreadingAllocateThreadPool(threadCountMaximum, 0, dAllocateFlagBasicData, NULL);
+    dThreadingThreadPoolServeMultiThreadedImplementation(pool, threading);
+
+    dResourceRequirementsID requirements = dResourceRequirementsCreate(cooperative);
+    dEstimateCooperativelySolveLDLTResourceRequirements(requirements, threadCountMaximum, COOP_MSIZE);
+    dResourceContainerID resources = dResourceContainerAcquire(requirements);
+
+    HEADER;
+
+    for (int pass = 0; pass != 4; ++pass)
+    {
+        dTimerStart ("Solving LDLT");
+
+        const unsigned allowedThreads = 4;
+        const unsigned PASS_MSIZE = COOP_MSIZE - pass, PASS_MSIZE4 = dALIGN_SIZE(PASS_MSIZE, 4);
+
+        dTimerNow ("Preparing data");
+        dMakeRandomMatrix (b, PASS_MSIZE, 1, 1.0);
+
+        dMakeRandomMatrix (L, PASS_MSIZE, PASS_MSIZE, 1.0);
+        dMultiply2 (A, L, L, PASS_MSIZE, PASS_MSIZE, PASS_MSIZE);
+
+        memcpy (x, b, PASS_MSIZE * sizeof(dReal));
+        memcpy (L, A, sizeof(dReal) * PASS_MSIZE4 * PASS_MSIZE);
+
+        dTimerNow ("Factoring");
+        dFactorLDLT (L, d, PASS_MSIZE, PASS_MSIZE4);
+
+        dTimerNow ("Solving multi-threaded");
+        dCooperativelySolveLDLT(resources, allowedThreads, L, d, x, PASS_MSIZE, PASS_MSIZE4);
+
+        dTimerNow ("Verifying solution");
+        dMultiply2 (btest, A, x, PASS_MSIZE, PASS_MSIZE, 1);
+        diff = dMaxDifference(b, btest, PASS_MSIZE, 1);
+        printf ("\tN=%u: maximum difference = %.6e - %s\n", PASS_MSIZE, diff, diff > 1e2 * tol ? "FAILED" : "passed");
+
+        dTimerEnd();
+        dTimerReport(stdout, 0);
+    }
+
+    dResourceContainerDestroy(resources);
+    dResourceRequirementsDestroy(requirements);
+
+    dThreadingImplementationShutdownProcessing(threading);
+    dThreadingFreeThreadPool(pool);
+    dCooperativeDestroy(cooperative);
+    dThreadingFreeImplementation(threading);
+
+    dFree(btest, vectorSize);
+    dFree(b, vectorSize);
+    dFree(x, vectorSize);
+    dFree(d, vectorSize);
+    dFree(L, matrixSize);
+    dFree(A, matrixSize);
+}
+
+
+void testLDLTAddTL()
+{
+    int i,j;
+    dsizeint matrixSize = sizeof(dReal) * MSIZE4 * MSIZE, vectorSize = sizeof(dReal) * MSIZE;
+    dReal *A = (dReal *)dAlloc(matrixSize), *L = (dReal *)dAlloc(matrixSize), 
+        *DL = (dReal *)dAlloc(matrixSize), *ATEST = (dReal *)dAlloc(matrixSize), 
+        *d = (dReal *)dAlloc(vectorSize), *a = (dReal *)dAlloc(vectorSize), diff;
+
+    HEADER;
+
+    dMakeRandomMatrix (A,MSIZE,MSIZE,1.0);
+    dMultiply2 (L,A,A,MSIZE,MSIZE,MSIZE);
+    memcpy (A,L,MSIZE4*MSIZE*sizeof(dReal));
+    dFactorLDLT (L,d,MSIZE,MSIZE4);
+
+    // delete first row and column of factorization
+    for (i=0; i<MSIZE; i++) a[i] = -A[i*MSIZE4];
+    a[0] += 1;
+    dLDLTAddTL (L,d,a,MSIZE,MSIZE4);
+    for (i=1; i<MSIZE; i++) L[i*MSIZE4] = 0;
+    d[0] = 1;
+
+    // get modified L*D*L'
+    dClearUpperTriangle (L,MSIZE);
+    for (i=0; i<MSIZE; i++) L[i*MSIZE4+i] = 1.0;
+    dSetZero (DL,MSIZE4*MSIZE);
+    for (i=0; i<MSIZE; i++) {
+        for (j=0; j<MSIZE; j++) DL[i*MSIZE4+j] = L[i*MSIZE4+j] / d[j];
+    }
+    dMultiply2 (ATEST,L,DL,MSIZE,MSIZE,MSIZE);
+
+    // compare it to A with its first row/column removed
+    for (i=1; i<MSIZE; i++) A[i*MSIZE4] = A[i] = 0;
+    A[0] = 1;
+    diff = dMaxDifference(A,ATEST,MSIZE,MSIZE);
+    printf ("\tmaximum difference = %.6e - %s\n",diff,
+        diff > tol ? "FAILED" : "passed");
+
+    dFree(a, vectorSize);
+    dFree(d, vectorSize);
+    dFree(ATEST, matrixSize);
+    dFree(DL, matrixSize);
+    dFree(L, matrixSize);
+    dFree(A, matrixSize);
+}
+
+
+void testLDLTRemove()
+{
+    int i,j,r;
+    dsizeint intVectorSize = sizeof(int) * MSIZE, matrixSize = sizeof(dReal) * MSIZE4 * MSIZE, vectorSize = sizeof(dReal) * MSIZE;
+    int *p = (int *)dAlloc(intVectorSize);
+    dReal *A = (dReal *)dAlloc(matrixSize), *L = (dReal *)dAlloc(matrixSize), 
+        *L2 = (dReal *)dAlloc(matrixSize), *DL2 = (dReal *)dAlloc(matrixSize), 
+        *Atest1 = (dReal *)dAlloc(matrixSize), *Atest2 = (dReal *)dAlloc(matrixSize), 
+        *d = (dReal *)dAlloc(vectorSize), *d2 = (dReal *)dAlloc(vectorSize), diff, maxdiff;
+
+    HEADER;
+
+    // make array of A row pointers
+    dReal *Arows[MSIZE];
+    for (i=0; i<MSIZE; i++) Arows[i] = A+i*MSIZE4;
+
+    // fill permutation vector
+    for (i=0; i<MSIZE; i++) p[i]=i;
+
+    dMakeRandomMatrix (A,MSIZE,MSIZE,1.0);
+    dMultiply2 (L,A,A,MSIZE,MSIZE,MSIZE);
+    memcpy (A,L,MSIZE4*MSIZE*sizeof(dReal));
+    dFactorLDLT (L,d,MSIZE,MSIZE4);
+
+    maxdiff = 1e10;
+    for (r=0; r<MSIZE; r++) {
+        // get Atest1 = A with row/column r removed
+        memcpy (Atest1,A,MSIZE4*MSIZE*sizeof(dReal));
+        dRemoveRowCol (Atest1,MSIZE,MSIZE4,r);
+
+        // test that the row/column removal worked
+        int bad = 0;
+        for (i=0; i<MSIZE; i++) {
+            for (j=0; j<MSIZE; j++) {
+                if (i != r && j != r) {
+                    int ii = i;
+                    int jj = j;
+                    if (ii >= r) ii--;
+                    if (jj >= r) jj--;
+                    if (A[i*MSIZE4+j] != Atest1[ii*MSIZE4+jj]) bad = 1;
+                }
+            }
+        }
+        if (bad) printf ("\trow/col removal FAILED for row %d\n",r);
+
+        // zero out last row/column of Atest1
+        for (i=0; i<MSIZE; i++) {
+            Atest1[(MSIZE-1)*MSIZE4+i] = 0;
+            Atest1[i*MSIZE4+MSIZE-1] = 0;
+        }    
+
+        // get L2*D2*L2' = adjusted factorization to remove that row
+        memcpy (L2,L,MSIZE4*MSIZE*sizeof(dReal));
+        memcpy (d2,d,MSIZE*sizeof(dReal));
+        dLDLTRemove (/*A*/ Arows,p,L2,d2,MSIZE,MSIZE,r,MSIZE4);
+
+        // get Atest2 = L2*D2*L2'
+        dClearUpperTriangle (L2,MSIZE);
+        for (i=0; i<(MSIZE-1); i++) L2[i*MSIZE4+i] = 1.0;
+        for (i=0; i<MSIZE; i++) L2[(MSIZE-1)*MSIZE4+i] = 0;
+        d2[MSIZE-1] = 1;
+        dSetZero (DL2,MSIZE4*MSIZE);
+        for (i=0; i<(MSIZE-1); i++) {
+            for (j=0; j<MSIZE-1; j++) DL2[i*MSIZE4+j] = L2[i*MSIZE4+j] / d2[j];
+        }
+
+        dMultiply2 (Atest2,L2,DL2,MSIZE,MSIZE,MSIZE);
+
+        diff = dMaxDifference(Atest1,Atest2,MSIZE,MSIZE);
+        if (diff < maxdiff) maxdiff = diff;
+
+        /*
+        dPrintMatrix (Atest1,MSIZE,MSIZE);
+        printf ("\n");
+        dPrintMatrix (Atest2,MSIZE,MSIZE);
+        printf ("\n");
+        */
+    }
+    printf ("\tmaximum difference = %.6e - %s\n",maxdiff,
+        maxdiff > tol ? "FAILED" : "passed");
+
+    dFree(d2, vectorSize);
+    dFree(d, vectorSize);
+    dFree(Atest2, matrixSize);
+    dFree(Atest1, matrixSize);
+    dFree(DL2, matrixSize);
+    dFree(L2, matrixSize);
+    dFree(L, matrixSize);
+    dFree(A, matrixSize);
+}
+
+//****************************************************************************
+// test mass stuff
+
+#define NUMP 10		// number of particles
+
+
+void printMassParams (dMass *m)
+{
+    printf ("mass = %.4f\n",m->mass);
+    printf ("com  = (%.4f,%.4f,%.4f)\n",m->c[0],m->c[1],m->c[2]);
+    printf ("I    = [ %10.4f %10.4f %10.4f ]\n"
+        "       [ %10.4f %10.4f %10.4f ]\n"
+        "       [ %10.4f %10.4f %10.4f ]\n",
+        m->_I(0,0),m->_I(0,1),m->_I(0,2),
+        m->_I(1,0),m->_I(1,1),m->_I(1,2),
+        m->_I(2,0),m->_I(2,1),m->_I(2,2));
+}
+
+
+void compareMassParams (dMass *m1, dMass *m2, const char *msg)
+{
+    int i,j,ok = 1;
+    if (!(cmp(m1->mass,m2->mass) && cmp(m1->c[0],m2->c[0]) &&
+        cmp(m1->c[1],m2->c[1]) && cmp(m1->c[2],m2->c[2])))
+        ok = 0;
+    for (i=0; i<3; i++) for (j=0; j<3; j++)
+        if (cmp (m1->_I(i,j),m2->_I(i,j))==0) ok = 0;
+    if (ok) printf ("\tpassed (%s)\n",msg); else printf ("\tFAILED (%s)\n",msg);
+}
+
+
+// compute the mass parameters of a particle set
+
+void computeMassParams (dMass *m, dReal q[NUMP][3], dReal pm[NUMP])
+{
+    int i,j;
+    dMassSetZero (m);
+    for (i=0; i<NUMP; i++) {
+        m->mass += pm[i];
+        for (j=0; j<3; j++) m->c[j] += pm[i]*q[i][j];
+        m->_I(0,0) += pm[i]*(q[i][1]*q[i][1] + q[i][2]*q[i][2]);
+        m->_I(1,1) += pm[i]*(q[i][0]*q[i][0] + q[i][2]*q[i][2]);
+        m->_I(2,2) += pm[i]*(q[i][0]*q[i][0] + q[i][1]*q[i][1]);
+        m->_I(0,1) -= pm[i]*(q[i][0]*q[i][1]);
+        m->_I(0,2) -= pm[i]*(q[i][0]*q[i][2]);
+        m->_I(1,2) -= pm[i]*(q[i][1]*q[i][2]);
+    }
+    for (j=0; j<3; j++) m->c[j] /= m->mass;
+    m->_I(1,0) = m->_I(0,1);
+    m->_I(2,0) = m->_I(0,2);
+    m->_I(2,1) = m->_I(1,2);
+}
+
+
+void testMassFunctions()
+{
+    dMass m;
+    int i,j;
+    dReal q[NUMP][3];		// particle positions
+    dReal pm[NUMP];		// particle masses
+    dMass m1,m2;
+    dMatrix3 R;
+
+    HEADER;
+
+    printf ("\t");
+    dMassSetZero (&m);
+    TRAP_MESSAGE (dMassSetParameters (&m,10, 0,0,0, 1,2,3, 4,5,6),
+        printf (" FAILED (1)\n"), printf (" passed (1)\n"));
+
+    printf ("\t");
+    dMassSetZero (&m);
+    TRAP_MESSAGE (dMassSetParameters (&m,10, 0.1,0.2,0.15, 3,5,14, 3.1,3.2,4),
+        printf ("passed (2)\n") , printf (" FAILED (2)\n"));
+    if (m.mass==10 && m.c[0]==REAL(0.1) && m.c[1]==REAL(0.2) &&
+        m.c[2]==REAL(0.15) && m._I(0,0)==3 && m._I(1,1)==5 && m._I(2,2)==14 &&
+        m._I(0,1)==REAL(3.1) && m._I(0,2)==REAL(3.2) && m._I(1,2)==4 &&
+        m._I(1,0)==REAL(3.1) && m._I(2,0)==REAL(3.2) && m._I(2,1)==4)
+        printf ("\tpassed (3)\n"); else printf ("\tFAILED (3)\n");
+
+    dMassSetZero (&m);
+    dMassSetSphere (&m,1.4, 0.86);
+    if (cmp(m.mass,3.73002719949386) && m.c[0]==0 && m.c[1]==0 && m.c[2]==0 &&
+        cmp(m._I(0,0),1.10349124669826) &&
+        cmp(m._I(1,1),1.10349124669826) &&
+        cmp(m._I(2,2),1.10349124669826) &&
+        m._I(0,1)==0 && m._I(0,2)==0 && m._I(1,2)==0 &&
+        m._I(1,0)==0 && m._I(2,0)==0 && m._I(2,1)==0)
+        printf ("\tpassed (4)\n"); else printf ("\tFAILED (4)\n");
+
+    dMassSetZero (&m);
+    dMassSetCapsule (&m,1.3,1,0.76,1.53);
+    if (cmp(m.mass,5.99961928996029) && m.c[0]==0 && m.c[1]==0 && m.c[2]==0 &&
+        cmp(m._I(0,0),1.59461986077384) &&
+        cmp(m._I(1,1),4.21878433864904) &&
+        cmp(m._I(2,2),4.21878433864904) &&
+        m._I(0,1)==0 && m._I(0,2)==0 && m._I(1,2)==0 &&
+        m._I(1,0)==0 && m._I(2,0)==0 && m._I(2,1)==0)
+        printf ("\tpassed (5)\n"); else printf ("\tFAILED (5)\n");
+
+    dMassSetZero (&m);
+    dMassSetBox (&m,0.27,3,4,5);
+    if (cmp(m.mass,16.2) && m.c[0]==0 && m.c[1]==0 && m.c[2]==0 &&
+        cmp(m._I(0,0),55.35) && cmp(m._I(1,1),45.9) && cmp(m._I(2,2),33.75) &&
+        m._I(0,1)==0 && m._I(0,2)==0 && m._I(1,2)==0 &&
+        m._I(1,0)==0 && m._I(2,0)==0 && m._I(2,1)==0)
+        printf ("\tpassed (6)\n"); else printf ("\tFAILED (6)\n");
+
+    // test dMassAdjust?
+
+    // make random particles and compute the mass, COM and inertia, then
+    // translate and repeat.
+    for (i=0; i<NUMP; i++) {
+        pm[i] = dRandReal()+0.5;
+        for (j=0; j<3; j++) {
+            q[i][j] = 2.0*(dRandReal()-0.5);
+        }
+    }
+    computeMassParams (&m1,q,pm);
+    memcpy (&m2,&m1,sizeof(dMass));
+    dMassTranslate (&m2,1,2,-3);
+    for (i=0; i<NUMP; i++) {
+        q[i][0] += 1;
+        q[i][1] += 2;
+        q[i][2] -= 3;
+    }
+    computeMassParams (&m1,q,pm);
+    compareMassParams (&m1,&m2,"7");
+
+    // rotate the masses
+    _R(0,0) = -0.87919618797635;
+    _R(0,1) = 0.15278881840384;
+    _R(0,2) = -0.45129772879842;
+    _R(1,0) = -0.47307856232664;
+    _R(1,1) = -0.39258064912909;
+    _R(1,2) = 0.78871864932708;
+    _R(2,0) = -0.05666336483842;
+    _R(2,1) = 0.90693771059546;
+    _R(2,2) = 0.41743652473765;
+    dMassRotate (&m2,R);
+    for (i=0; i<NUMP; i++) {
+        dReal a[3];
+        dMultiply0 (a,&_R(0,0),&q[i][0],3,3,1);
+        q[i][0] = a[0];
+        q[i][1] = a[1];
+        q[i][2] = a[2];
+    }
+    computeMassParams (&m1,q,pm);
+    compareMassParams (&m1,&m2,"8");
+}
+
+//****************************************************************************
+// test rotation stuff
+
+void makeRandomRotation (dMatrix3 R)
+{
+    dReal *u1 = R, *u2=R+4, *u3=R+8;
+    dMakeRandomVector (u1,3,1.0);
+    dNormalize3 (u1);
+    dMakeRandomVector (u2,3,1.0);
+    dReal d = dCalcVectorDot3(u1,u2);
+    u2[0] -= d*u1[0];
+    u2[1] -= d*u1[1];
+    u2[2] -= d*u1[2];
+    dNormalize3(u2);
+    dCalcVectorCross3(u3,u1,u2);
+}
+
+
+void testRtoQandQtoR()
+{
+    HEADER;
+    dMatrix3 R,I,R2;
+    dQuaternion q;
+    int i;
+
+    // test makeRandomRotation()
+    makeRandomRotation (R);
+    dMultiply2 (I,R,R,3,3,3);
+    printf ("\tmakeRandomRotation() - %s (1)\n",
+        cmpIdentityMat3(I) ? "passed" : "FAILED");
+
+    // test QtoR() on random normalized quaternions
+    int ok = 1;
+    for (i=0; i<100; i++) {
+        dMakeRandomVector (q,4,1.0);
+        dNormalize4 (q);
+        dQtoR (q,R);
+        dMultiply2 (I,R,R,3,3,3);
+        if (cmpIdentityMat3(I)==0) ok = 0;
+    }
+    printf ("\tQtoR() orthonormality %s (2)\n", ok ? "passed" : "FAILED");
+
+    // test R -> Q -> R works
+    dReal maxdiff=0;
+    for (i=0; i<100; i++) {
+        makeRandomRotation (R);
+        dRtoQ (R,q);
+        dQtoR (q,R2);
+        dReal diff = dMaxDifference (R,R2,3,3);
+        if (diff > maxdiff) maxdiff = diff;
+    }
+    printf ("\tmaximum difference = %e - %s (3)\n",maxdiff,
+        (maxdiff > tol) ? "FAILED" : "passed");
+}
+
+
+void testQuaternionMultiply()
+{
+    HEADER;
+    dMatrix3 RA,RB,RC,Rtest;
+    dQuaternion qa,qb,qc;
+    dReal diff,maxdiff=0;
+
+    for (int i=0; i<100; i++) {
+        makeRandomRotation (RB);
+        makeRandomRotation (RC);
+        dRtoQ (RB,qb);
+        dRtoQ (RC,qc);
+
+        dMultiply0 (RA,RB,RC,3,3,3);
+        dQMultiply0 (qa,qb,qc);
+        dQtoR (qa,Rtest);
+        diff = dMaxDifference (Rtest,RA,3,3);
+        if (diff > maxdiff) maxdiff = diff;
+
+        dMultiply1 (RA,RB,RC,3,3,3);
+        dQMultiply1 (qa,qb,qc);
+        dQtoR (qa,Rtest);
+        diff = dMaxDifference (Rtest,RA,3,3);
+        if (diff > maxdiff) maxdiff = diff;
+
+        dMultiply2 (RA,RB,RC,3,3,3);
+        dQMultiply2 (qa,qb,qc);
+        dQtoR (qa,Rtest);
+        diff = dMaxDifference (Rtest,RA,3,3);
+        if (diff > maxdiff) maxdiff = diff;
+
+        dMultiply0 (RA,RC,RB,3,3,3);
+        transpose3x3 (RA);
+        dQMultiply3 (qa,qb,qc);
+        dQtoR (qa,Rtest);
+        diff = dMaxDifference (Rtest,RA,3,3);
+        if (diff > maxdiff) maxdiff = diff;
+    }
+    printf ("\tmaximum difference = %e - %s\n",maxdiff,
+        (maxdiff > tol) ? "FAILED" : "passed");
+}
+
+
+void testRotationFunctions()
+{
+    dMatrix3 R1;
+    HEADER;
+
+    printf ("\tdRSetIdentity - ");
+    dMakeRandomMatrix (R1,3,3,1.0);
+    dRSetIdentity (R1);
+    if (cmpIdentityMat3(R1)) printf ("passed\n"); else printf ("FAILED\n");
+
+    printf ("\tdRFromAxisAndAngle - ");
+
+    printf ("\n");
+    printf ("\tdRFromEulerAngles - ");
+
+    printf ("\n");
+    printf ("\tdRFrom2Axes - ");
+
+    printf ("\n");
+}
+
+//****************************************************************************
+
+#include <assert.h>
+
+template<class T>
+class simplevector
+{
+private:
+    int n;
+    int max;
+    T* data;
+
+public:
+    simplevector() { initialize(); }
+    ~simplevector() { finalize(); }
+    T& operator[](int i) { assert(i>=0 && i<n); return data[i]; }
+    const T& operator[](int i) const { assert(i>=0 && i<n); return data[i]; }
+    void push_back(const T& elem)
+    {
+        if (n == max)
+        {
+            max *= 2;
+            T* newdata = new T[max];
+            memcpy(newdata, data, sizeof(T)*n);
+            delete[] data;
+            data = newdata;
+        }
+        data[n++] = elem;
+    }
+    int size() const { return n; }
+    void clear() { finalize(); initialize(); }
+
+private:
+    void finalize() { delete[] data; }
+    void initialize() { data = new T[32]; max = 32; n = 0; }
+};
+
+// matrix header on the stack
+
+class dMatrixComparison {
+    struct dMatInfo;
+    simplevector<dMatInfo*> mat;
+    int afterfirst,index;
+
+public:
+    dMatrixComparison();
+    ~dMatrixComparison();
+
+    dReal nextMatrix (dReal *A, int n, int m, int lower_tri, const char *name, ...);
+    // add a new n*m matrix A to the sequence. the name of the matrix is given
+    // by the printf-style arguments (name,...). if this is the first sequence
+    // then this object will simply record the matrices and return 0.
+    // if this the second or subsequent sequence then this object will compare
+    // the matrices with the first sequence, and report any differences.
+    // the matrix error will be returned. if `lower_tri' is 1 then only the
+    // lower triangle of the matrix (including the diagonal) will be compared
+    // (the matrix must be square).
+
+    void end();
+    // end a sequence.
+
+    void reset();
+    // restarts the object, so the next sequence will be the first sequence.
+
+    void dump();
+    // print out info about all the matrices in the sequence
+};
+
+struct dMatrixComparison::dMatInfo {
+    int n,m;		// size of matrix
+    char name[128];	// name of the matrix
+    dReal *data;		// matrix data
+    int size;		// size of `data'
+};
+
+
+
+dMatrixComparison::dMatrixComparison()
+{
+    afterfirst = 0;
+    index = 0;
+}
+
+
+dMatrixComparison::~dMatrixComparison()
+{
+    reset();
+}
+
+
+dReal dMatrixComparison::nextMatrix (dReal *A, int n, int m, int lower_tri,
+                                     const char *name, ...)
+{
+    if (A==0 || n < 1 || m < 1 || name==0) dDebug (0,"bad args to nextMatrix");
+    int num = n*dPAD(m);
+
+    if (afterfirst==0) {
+        dMatInfo *mi = (dMatInfo*) dAlloc (sizeof(dMatInfo));
+        mi->n = n;
+        mi->m = m;
+        mi->size = num * sizeof(dReal);
+        mi->data = (dReal*) dAlloc (mi->size);
+        memcpy (mi->data,A,mi->size);
+
+        va_list ap;
+        va_start (ap,name);
+        vsprintf (mi->name,name,ap);
+        va_end (ap);
+        if (strlen(mi->name) >= sizeof (mi->name)) dDebug (0,"name too long");
+
+        mat.push_back(mi);
+        return 0;
+    }
+    else {
+        if (lower_tri && n != m)
+            dDebug (0,"dMatrixComparison, lower triangular matrix must be square");
+        if (index >= mat.size()) dDebug (0,"dMatrixComparison, too many matrices");
+        dMatInfo *mp = mat[index];
+        index++;
+
+        dMatInfo mi;
+        va_list ap;
+        va_start (ap,name);
+        vsprintf (mi.name,name,ap);
+        va_end (ap);
+        if (strlen(mi.name) >= sizeof (mi.name)) dDebug (0,"name too long");
+
+        if (strcmp(mp->name,mi.name) != 0)
+            dDebug (0,"dMatrixComparison, name mismatch (\"%s\" and \"%s\")",
+            mp->name,mi.name);
+        if (mp->n != n || mp->m != m)
+            dDebug (0,"dMatrixComparison, size mismatch (%dx%d and %dx%d)",
+            mp->n,mp->m,n,m);
+
+        dReal maxdiff;
+        if (lower_tri) {
+            maxdiff = dMaxDifferenceLowerTriangle (A,mp->data,n);
+        }
+        else {
+            maxdiff = dMaxDifference (A,mp->data,n,m);
+        }
+        if (maxdiff > tol)
+            dDebug (0,"dMatrixComparison, matrix error (size=%dx%d, name=\"%s\", "
+            "error=%.4e)",n,m,mi.name,maxdiff);
+        return maxdiff;
+    }
+}
+
+
+void dMatrixComparison::end()
+{
+    if (mat.size() <= 0) dDebug (0,"no matrices in sequence");
+    afterfirst = 1;
+    index = 0;
+}
+
+
+void dMatrixComparison::reset()
+{
+    for (int i=0; i<mat.size(); i++) {
+        dFree (mat[i]->data,mat[i]->size);
+        dFree (mat[i],sizeof(dMatInfo));
+    }
+    mat.clear();
+    afterfirst = 0;
+    index = 0;
+}
+
+
+void dMatrixComparison::dump()
+{
+    for (int i=0; i<mat.size(); i++)
+        printf ("%d: %s (%dx%d)\n",i,mat[i]->name,mat[i]->n,mat[i]->m);
+}
+
+//****************************************************************************
+// unit test
+
+#include <setjmp.h>
+
+// static jmp_buf jump_buffer;
+
+static void myDebug (int /*num*/, const char* /*msg*/, va_list /*ap*/)
+{
+    // printf ("(Error %d: ",num);
+    // vprintf (msg,ap);
+    // printf (")\n");
+    longjmp (jump_buffer,1);
+}
+
+
+extern "C" void dTestMatrixComparison()
+{
+    volatile int i;
+    printf ("dTestMatrixComparison()\n");
+    dMessageFunction *orig_debug = dGetDebugHandler();
+
+    dMatrixComparison mc;
+    dReal A[50*50];
+
+    // make first sequence
+    unsigned long seed = dRandGetSeed();
+    for (i=1; i<49; i++) {
+        dMakeRandomMatrix (A,i,i+1,1.0);
+        mc.nextMatrix (A,i,i+1,0,"A%d",i);
+    }
+    mc.end();
+
+    //mc.dump();
+
+    // test identical sequence
+    dSetDebugHandler (&myDebug);
+    dRandSetSeed (seed);
+    if (setjmp (jump_buffer)) {
+        printf ("\tFAILED (1)\n");
+    }
+    else {
+        for (i=1; i<49; i++) {
+            dMakeRandomMatrix (A,i,i+1,1.0);
+            mc.nextMatrix (A,i,i+1,0,"A%d",i);
+        }
+        mc.end();
+        printf ("\tpassed (1)\n");
+    }
+    dSetDebugHandler (orig_debug);
+
+    // test broken sequences (with matrix error)
+    dRandSetSeed (seed);
+    volatile int passcount = 0;
+    for (i=1; i<49; i++) {
+        if (setjmp (jump_buffer)) {
+            passcount++;
+        }
+        else {
+            dSetDebugHandler (&myDebug);
+            dMakeRandomMatrix (A,i,i+1,1.0);
+            A[(i-1)*dPAD(i+1)+i] += REAL(0.01);
+            mc.nextMatrix (A,i,i+1,0,"A%d",i);
+            dSetDebugHandler (orig_debug);
+        }
+    }
+    mc.end();
+    printf ("\t%s (2)\n",(passcount == 48) ? "passed" : "FAILED");
+
+    // test broken sequences (with name error)
+    dRandSetSeed (seed);
+    passcount = 0;
+    for (i=1; i<49; i++) {
+        if (setjmp (jump_buffer)) {
+            passcount++;
+        }
+        else {
+            dSetDebugHandler (&myDebug);
+            dMakeRandomMatrix (A,i,i+1,1.0);
+            mc.nextMatrix (A,i,i+1,0,"B%d",i);
+            dSetDebugHandler (orig_debug);
+        }
+    }
+    mc.end();
+    printf ("\t%s (3)\n",(passcount == 48) ? "passed" : "FAILED");
+
+    // test identical sequence again
+    dSetDebugHandler (&myDebug);
+    dRandSetSeed (seed);
+    if (setjmp (jump_buffer)) {
+        printf ("\tFAILED (4)\n");
+    }
+    else {
+        for (i=1; i<49; i++) {
+            dMakeRandomMatrix (A,i,i+1,1.0);
+            mc.nextMatrix (A,i,i+1,0,"A%d",i);
+        }
+        mc.end();
+        printf ("\tpassed (4)\n");
+    }
+    dSetDebugHandler (orig_debug);
+}
+
+//****************************************************************************
+
+// internal unit tests
+extern "C" void dTestDataStructures();
+extern "C" void dTestMatrixComparison();
+extern "C" int dTestSolveLCP();
+
+
+int main()
+{
+    dInitODE();
+    testRandomNumberGenerator();
+    testInfinity();
+    testPad();
+    testCrossProduct();
+    testSetZero();
+    testNormalize3();
+    //testReorthonormalize();     ... not any more
+    testPlaneSpace();
+    testMatrixMultiply();
+    testSmallMatrixMultiply();
+    testCholeskyFactorization();
+    testCholeskySolve();
+    testInvertPDMatrix();
+    testIsPositiveDefinite();
+    testFastLDLTFactorization();
+    testCoopLDLTFactorization();
+    testSolveLDLT();
+    testCoopSolveLDLT();
+    testLDLTAddTL();
+    testLDLTRemove();
+    testMassFunctions();
+    testRtoQandQtoR();
+    testQuaternionMultiply();
+    testRotationFunctions();
+    dTestMatrixComparison();
+    dTestSolveLCP();
+    // dTestDataStructures();
+    dCloseODE();
+    return 0;
+}