Remove mjData.qM

PiperOrigin-RevId: 942520660
Change-Id: I422358e299ca0fcfe4c49cd0ee90c014a4c319d7

src/engine/engine_core_smooth.c

@@ -1871,7 +1871,6 @@ void mj_makeM(const mjModel* m, mjData* d) {
   TM_START;
   mj_crb(m, d);
   mj_tendonArmature(m, d);
-  mju_scatter(d->qM, d->M, m->mapM2M, m->nC);  // TODO(tassa): scatter only awake dofs
   TM_END(mjTIMER_POS_INERTIA);
 }
 

src/engine/engine_inverse.c

@@ -132,10 +132,10 @@ static void mj_discreteAcc(const mjModel* m, mjData* d) {
     // compute qDeriv
     mjd_smooth_vel(m, d, /* flg_bias = */ 1);
 
-    // gather qLU <- qM (lower to full)
+    // gather qLU <- M (lower to full)
     mju_gatherMasked(d->qLU, d->M, m->mapM2D, nD);
 
-    // set qLU = qM - dt*qDeriv
+    // set qLU = M - dt*qDeriv
     mju_addToScl(d->qLU, d->qDeriv, -m->opt.timestep, m->nD);
 
     // set qfrc = qLU * qacc

src/engine/engine_io.c

@@ -1446,9 +1446,6 @@ static void _resetData(const mjModel* m, mjData* d, unsigned char debug_value) {
     }
   }
 
-  // zero out qM, special case because scattering from M skips simple body off-diagonals
-  mju_zero(d->qM, m->nM);
-
   // copy qpos0 from model
   if (m->qpos0) {
     mju_copy(d->qpos, m->qpos0, m->nq);

src/engine/engine_print.c

@@ -242,41 +242,6 @@ static void printBlockArray(const char* str, const mjtNum* data, int nc,
 }
 
 
-// print sparse inertia-like matrix
-static void printInertia(const char* str, const mjtNum* mat, const mjModel* m,
-                         FILE* fp, const char* float_format) {
-  int nv = m->nv;
-  // if no data, or too many rows to be visually useful, return
-  if (!mat || !nv || nv > 300) {
-    return;
-  }
-
-  // get length of string produced by float_format
-  char test[100];
-  int len = snprintf(test, sizeof(test), float_format, 0.0);
-
-  fprintf(fp, "%s\n", str);
-
-  for (int i=0; i < nv; i++) {
-    fprintf(fp, " ");
-    int adr = (i == nv-1) ? m->nM - 1 : m->dof_Madr[i+1] - 1;
-    for (int k=0; k <= i; k++) {
-      int j = i;
-      while (j != k && j >= 0) {
-        j = m->dof_parentid[j];
-      }
-      if (j == k) {
-        fprintf(fp, " ");
-        fprintf(fp, float_format, mat[adr--]);
-      } else {
-        for (int d=0; d < len+1; d++) fprintf(fp, " ");
-      }
-    }
-    fprintf(fp, "\n");
-  }
-  fprintf(fp, "\n");
-}
-
 
 // print sparse matrix structure
 void mj_printSparsity(const char* str, int nr, int nc, const int* rowadr, const int* diag,
@@ -1464,7 +1429,6 @@ void mj_printFormattedData(const mjModel* m, const mjData* d, const char* filena
   printSparse("ACTUATOR_MOMENT", d->actuator_moment, m->nu, d->moment_rownnz,
               d->moment_rowadr, d->moment_colind, fp, float_format);
   printArray2d("CRB", m->nbody, 10, d->crb, fp, float_format);
-  printInertia("QM", d->qM, m, fp, float_format);
   printSparse("M", d->M, m->nv, m->M_rownnz,
               m->M_rowadr, m->M_colind, fp, float_format);
   printSparse("QLD", d->qLD, m->nv, m->M_rownnz,