Remove mjData.C_diag, no longer required as C is now lower triangular.

PiperOrigin-RevId: 712514204
Change-Id: I8293f65ebc09c6a8fed76b0e59d2e2a667e01a43

Author: yuvaltassa

doc/includes/references.h

@@ -313,7 +313,6 @@ struct mjData_ {
   int*    B_colind;          // body-dof: column indices of non-zeros            (nB x 1)
   int*    C_rownnz;          // reduced dof-dof: non-zeros in each row           (nv x 1)
   int*    C_rowadr;          // reduced dof-dof: address of each row in C_colind (nv x 1)
-  int*    C_diag;            // reduced dof-dof: index of diagonal element       (nv x 1)
   int*    C_colind;          // reduced dof-dof: column indices of non-zeros     (nC x 1)
   int*    mapM2C;            // index mapping from M to C                        (nC x 1)
   int*    D_rownnz;          // dof-dof: non-zeros in each row                   (nv x 1)

include/mujoco/mjdata.h

@@ -341,7 +341,6 @@ struct mjData_ {
   int*    B_colind;          // body-dof: column indices of non-zeros            (nB x 1)
   int*    C_rownnz;          // reduced dof-dof: non-zeros in each row           (nv x 1)
   int*    C_rowadr;          // reduced dof-dof: address of each row in C_colind (nv x 1)
-  int*    C_diag;            // reduced dof-dof: index of diagonal element       (nv x 1)
   int*    C_colind;          // reduced dof-dof: column indices of non-zeros     (nC x 1)
   int*    mapM2C;            // index mapping from M to C                        (nC x 1)
   int*    D_rownnz;          // dof-dof: non-zeros in each row                   (nv x 1)

include/mujoco/mjxmacro.h

@@ -654,7 +654,6 @@
     X   ( int,       B_colind,          nB,          1           ) \
     X   ( int,       C_rownnz,          nv,          1           ) \
     X   ( int,       C_rowadr,          nv,          1           ) \
-    X   ( int,       C_diag,            nv,          1           ) \
     X   ( int,       C_colind,          nC,          1           ) \
     X   ( int,       mapM2C,            nC,          1           ) \
     X   ( int,       D_rownnz,          nv,          1           ) \

introspect/structs.py

@@ -5388,14 +5388,6 @@
                  ),
                  doc='reduced dof-dof: address of each row in C_colind (nv x 1)',  # pylint: disable=line-too-long
              ),
-             StructFieldDecl(
-                 name='C_diag',
-                 type=PointerType(
-                     inner_type=ValueType(name='int'),
-                 ),
-                 doc='reduced dof-dof: index of diagonal element',
-                 array_extent=('nv',),
-             ),
              StructFieldDecl(
                  name='C_colind',
                  type=PointerType(

mjx/mujoco/mjx/_src/io.py

@@ -332,7 +332,6 @@ def make_data(
         'B_colind': (m.nB, jp.int32),
         'C_rownnz': (m.nv, jp.int32),
         'C_rowadr': (m.nv, jp.int32),
-        'C_diag': (m.nv, jp.int32),
         'C_colind': (m.nC, jp.int32),
         'mapM2C': (m.nC, jp.int32),
         'D_rownnz': (m.nv, jp.int32),

mjx/mujoco/mjx/_src/types.py

@@ -1296,7 +1296,6 @@ class Data(PyTreeNode):
     B_colind: body-dof: column indices of non-zeros             (nB,)
     C_rownnz: reduced dof-dof: non-zeros in each row            (nv,)
     C_rowadr: reduced dof-dof: address of each row in C_colind  (nv,)
-    C_diag: reduced dof-dof: index of diagonal element          (nv,)
     C_colind: reduced dof-dof: column indices of non-zeros      (nC,)
     mapM2C: index mapping from M to C                           (nC,)
     D_rownnz: dof-dof: non-zeros in each row                    (nv,)
@@ -1426,7 +1425,6 @@ class Data(PyTreeNode):
   B_colind: jax.Array = _restricted_to('mujoco')  # pylint:disable=invalid-name
   C_rownnz: jax.Array = _restricted_to('mujoco')  # pylint:disable=invalid-name
   C_rowadr: jax.Array = _restricted_to('mujoco')  # pylint:disable=invalid-name
-  C_diag: jax.Array = _restricted_to('mujoco')  # pylint:disable=invalid-name
   C_colind: jax.Array = _restricted_to('mujoco')  # pylint:disable=invalid-name
   mapM2C: jax.Array = _restricted_to('mujoco')  # pylint:disable=invalid-name
   D_rownnz: jax.Array = _restricted_to('mujoco')  # pylint:disable=invalid-name

src/engine/engine_io.c

@@ -994,16 +994,18 @@ static void makeDofDofSparse(const mjModel* m, mjData* d,
   }
 
   // find diagonal indices
-  for (int i = 0; i < nv; i++) {
-    int adr = rowadr[i];
-    int j = 0;
-    while (colind[adr + j] < i && j < rownnz[i]) {
-      j++;
-    }
-    if (colind[adr + j] != i) {
-      mjERROR("diagonal index not found");
+  if (diag) {
+    for (int i = 0; i < nv; i++) {
+      int adr = rowadr[i];
+      int j = 0;
+      while (colind[adr + j] < i && j < rownnz[i]) {
+        j++;
+      }
+      if (colind[adr + j] != i) {
+        mjERROR("diagonal index not found");
+      }
+      diag[i] = j;
     }
-    diag[i] = j;
   }
 
   mj_freeStack(d);
@@ -1963,7 +1965,7 @@ static void _resetData(const mjModel* m, mjData* d, unsigned char debug_value) {
     checkDBSparse(m, d);
 
     // make C
-    makeDofDofSparse(m, d, d->C_rownnz, d->C_rowadr, d->C_diag, d->C_colind, /*reduced=*/1);
+    makeDofDofSparse(m, d, d->C_rownnz, d->C_rowadr, NULL, d->C_colind, /*reduced=*/1);
     makeDofDofmap(m, d);
   }
 

src/engine/engine_print.c

@@ -1135,7 +1135,7 @@ void mj_printFormattedData(const mjModel* m, mjData* d, const char* filename,
   fprintf(fp, "\n\n");
 
   // C sparse structure
-  mj_printSparsity("C: reduced dof-dof matrix", m->nv, m->nv, d->C_rowadr, d->C_diag, d->C_rownnz,
+  mj_printSparsity("C: reduced dof-dof matrix", m->nv, m->nv, d->C_rowadr, NULL, d->C_rownnz,
                    NULL, d->C_colind, fp);
 
   fprintf(fp, NAME_FORMAT, "C_rownnz");

unity/Runtime/Bindings/MjBindings.cs

@@ -4939,7 +4939,6 @@ public unsafe struct mjData_ {
   public int* B_colind;
   public int* C_rownnz;
   public int* C_rowadr;
-  public int* C_diag;
   public int* C_colind;
   public int* mapM2C;
   public int* D_rownnz;