Sparse ten_J and ten_J_colind memory

PiperOrigin-RevId: 868834376
Change-Id: Iec92d9e09e3134666895e54a78cb02439d74a4de

src/user/user_model.cc

@@ -3226,16 +3226,7 @@ int mjCModel::CountNJmom(const mjModel* m) {
   return count;
 }
 
-// compute non-zeros in ten_J matrix
-int mjCModel::CountNJten(const mjModel* m) {
-  int nv = m->nv;
-  int ntendon = m->ntendon;
 
-  // conservative upper bound: each tendon can have at most nv non-zeros
-  // TODO(taylorhowell): compute tighter bound
-  int count = ntendon * nv;
-  return count;
-}
 
 // copy objects outside kinematic tree
 void mjCModel::CopyObjects(mjModel* m) {
@@ -5046,9 +5037,6 @@ void mjCModel::TryCompile(mjModel*& m, mjData*& d, const mjVFS* vfs) {
   // compute non-zeros in actuator_moment
   m->nJmom = nJmom = CountNJmom(m);
 
-  // compute non-zeros in ten_J
-  m->nJten = nJten = CountNJten(m);
-
   // scale mass
   if (compiler.settotalmass > 0) {
     mj_setTotalmass(m, compiler.settotalmass);