Remove transposed Jacobian fields from mjData

No longer computed unconditionally, only ad-hoc where required.

PiperOrigin-RevId: 797753297
Change-Id: I2030fc342c98ff33575b0526dd72e2110c4fcb74

doc/includes/references.h

@@ -349,12 +349,7 @@ struct mjData_ {
   int*    efc_J_rowadr;      // row start address in colind array                (nefc x 1)
   int*    efc_J_rowsuper;    // number of subsequent rows in supernode           (nefc x 1)
   int*    efc_J_colind;      // column indices in constraint Jacobian            (nJ x 1)
-  int*    efc_JT_rownnz;     // number of non-zeros in constraint Jacobian row T (nv x 1)
-  int*    efc_JT_rowadr;     // row start address in colind array              T (nv x 1)
-  int*    efc_JT_rowsuper;   // number of subsequent rows in supernode         T (nv x 1)
-  int*    efc_JT_colind;     // column indices in constraint Jacobian          T (nJ x 1)
   mjtNum* efc_J;             // constraint Jacobian                              (nJ x 1)
-  mjtNum* efc_JT;            // constraint Jacobian transposed                   (nJ x 1)
   mjtNum* efc_pos;           // constraint position (equality, contact)          (nefc x 1)
   mjtNum* efc_margin;        // inclusion margin (contact)                       (nefc x 1)
   mjtNum* efc_frictionloss;  // frictionloss (friction)                          (nefc x 1)
@@ -399,12 +394,7 @@ struct mjData_ {
   int*    iefc_J_rowadr;     // row start address in colind array                (nefc x 1)
   int*    iefc_J_rowsuper;   // number of subsequent rows in supernode           (nefc x 1)
   int*    iefc_J_colind;     // column indices in constraint Jacobian            (nJ x 1)
-  int*    iefc_JT_rownnz;    // number of non-zeros in constraint Jacobian row T (nidof x 1)
-  int*    iefc_JT_rowadr;    // row start address in colind array              T (nidof x 1)
-  int*    iefc_JT_rowsuper;  // number of subsequent rows in supernode         T (nidof x 1)
-  int*    iefc_JT_colind;    // column indices in constraint Jacobian          T (nJ x 1)
   mjtNum* iefc_J;            // constraint Jacobian                              (nJ x 1)
-  mjtNum* iefc_JT;           // constraint Jacobian transposed                   (nJ x 1)
   mjtNum* iefc_frictionloss; // frictionloss (friction)                          (nefc x 1)
   mjtNum* iefc_D;            // constraint mass                                  (nefc x 1)
   mjtNum* iefc_R;            // inverse constraint mass                          (nefc x 1)

include/mujoco/mjdata.h

@@ -377,12 +377,7 @@ struct mjData_ {
   int*    efc_J_rowadr;      // row start address in colind array                (nefc x 1)
   int*    efc_J_rowsuper;    // number of subsequent rows in supernode           (nefc x 1)
   int*    efc_J_colind;      // column indices in constraint Jacobian            (nJ x 1)
-  int*    efc_JT_rownnz;     // number of non-zeros in constraint Jacobian row T (nv x 1)
-  int*    efc_JT_rowadr;     // row start address in colind array              T (nv x 1)
-  int*    efc_JT_rowsuper;   // number of subsequent rows in supernode         T (nv x 1)
-  int*    efc_JT_colind;     // column indices in constraint Jacobian          T (nJ x 1)
   mjtNum* efc_J;             // constraint Jacobian                              (nJ x 1)
-  mjtNum* efc_JT;            // constraint Jacobian transposed                   (nJ x 1)
   mjtNum* efc_pos;           // constraint position (equality, contact)          (nefc x 1)
   mjtNum* efc_margin;        // inclusion margin (contact)                       (nefc x 1)
   mjtNum* efc_frictionloss;  // frictionloss (friction)                          (nefc x 1)
@@ -427,12 +422,7 @@ struct mjData_ {
   int*    iefc_J_rowadr;     // row start address in colind array                (nefc x 1)
   int*    iefc_J_rowsuper;   // number of subsequent rows in supernode           (nefc x 1)
   int*    iefc_J_colind;     // column indices in constraint Jacobian            (nJ x 1)
-  int*    iefc_JT_rownnz;    // number of non-zeros in constraint Jacobian row T (nidof x 1)
-  int*    iefc_JT_rowadr;    // row start address in colind array              T (nidof x 1)
-  int*    iefc_JT_rowsuper;  // number of subsequent rows in supernode         T (nidof x 1)
-  int*    iefc_JT_colind;    // column indices in constraint Jacobian          T (nJ x 1)
   mjtNum* iefc_J;            // constraint Jacobian                              (nJ x 1)
-  mjtNum* iefc_JT;           // constraint Jacobian transposed                   (nJ x 1)
   mjtNum* iefc_frictionloss; // frictionloss (friction)                          (nefc x 1)
   mjtNum* iefc_D;            // constraint mass                                  (nefc x 1)
   mjtNum* iefc_R;            // inverse constraint mass                          (nefc x 1)

include/mujoco/mjxmacro.h

@@ -729,12 +729,7 @@
     XNV( int,      efc_J_rowadr,      MJ_D(nefc),    1 ) \
     XNV( int,      efc_J_rowsuper,    MJ_D(nefc),    1 ) \
     XNV( int,      efc_J_colind,      MJ_D(nJ),      1 ) \
-    XNV( int,      efc_JT_rownnz,     MJ_M(nv),      1 ) \
-    XNV( int,      efc_JT_rowadr,     MJ_M(nv),      1 ) \
-    XNV( int,      efc_JT_rowsuper,   MJ_M(nv),      1 ) \
-    XNV( int,      efc_JT_colind,     MJ_D(nJ),      1 ) \
     XNV( mjtNum,   efc_J,             MJ_D(nJ),      1 ) \
-    XNV( mjtNum,   efc_JT,            MJ_D(nJ),      1 ) \
     X  ( mjtNum,   efc_pos,           MJ_D(nefc),    1 ) \
     X  ( mjtNum,   efc_margin,        MJ_D(nefc),    1 ) \
     X  ( mjtNum,   efc_frictionloss,  MJ_D(nefc),    1 ) \
@@ -786,12 +781,7 @@
     XNV( int,     iefc_J_rowadr,     MJ_D(nefc),     1 ) \
     XNV( int,     iefc_J_rowsuper,   MJ_D(nefc),     1 ) \
     XNV( int,     iefc_J_colind,     MJ_D(nJ),       1 ) \
-    XNV( int,     iefc_JT_rownnz,    MJ_D(nidof),    1 ) \
-    XNV( int,     iefc_JT_rowadr,    MJ_D(nidof),    1 ) \
-    XNV( int,     iefc_JT_rowsuper,  MJ_D(nidof),    1 ) \
-    XNV( int,     iefc_JT_colind,    MJ_D(nJ),       1 ) \
     XNV( mjtNum,  iefc_J,            MJ_D(nJ),       1 ) \
-    XNV( mjtNum,  iefc_JT,           MJ_D(nJ),       1 ) \
     X  ( mjtNum,  iefc_frictionloss, MJ_D(nefc),     1 ) \
     X  ( mjtNum,  iefc_D,            MJ_D(nefc),     1 ) \
     X  ( mjtNum,  iefc_R,            MJ_D(nefc),     1 ) \

python/mujoco/introspect/structs.py

@@ -5914,38 +5914,6 @@ STRUCTS: Mapping[str, StructDecl] = dict([
                  doc='column indices in constraint Jacobian',
                  array_extent=('nJ',),
              ),
-             StructFieldDecl(
-                 name='efc_JT_rownnz',
-                 type=PointerType(
-                     inner_type=ValueType(name='int'),
-                 ),
-                 doc='number of non-zeros in constraint Jacobian row T',
-                 array_extent=('nv',),
-             ),
-             StructFieldDecl(
-                 name='efc_JT_rowadr',
-                 type=PointerType(
-                     inner_type=ValueType(name='int'),
-                 ),
-                 doc='row start address in colind array              T',
-                 array_extent=('nv',),
-             ),
-             StructFieldDecl(
-                 name='efc_JT_rowsuper',
-                 type=PointerType(
-                     inner_type=ValueType(name='int'),
-                 ),
-                 doc='number of subsequent rows in supernode         T',
-                 array_extent=('nv',),
-             ),
-             StructFieldDecl(
-                 name='efc_JT_colind',
-                 type=PointerType(
-                     inner_type=ValueType(name='int'),
-                 ),
-                 doc='column indices in constraint Jacobian          T',
-                 array_extent=('nJ',),
-             ),
              StructFieldDecl(
                  name='efc_J',
                  type=PointerType(
@@ -5954,14 +5922,6 @@ STRUCTS: Mapping[str, StructDecl] = dict([
                  doc='constraint Jacobian',
                  array_extent=('nJ',),
              ),
-             StructFieldDecl(
-                 name='efc_JT',
-                 type=PointerType(
-                     inner_type=ValueType(name='mjtNum'),
-                 ),
-                 doc='constraint Jacobian transposed',
-                 array_extent=('nJ',),
-             ),
              StructFieldDecl(
                  name='efc_pos',
                  type=PointerType(
@@ -6250,38 +6210,6 @@ STRUCTS: Mapping[str, StructDecl] = dict([
                  doc='column indices in constraint Jacobian',
                  array_extent=('nJ',),
              ),
-             StructFieldDecl(
-                 name='iefc_JT_rownnz',
-                 type=PointerType(
-                     inner_type=ValueType(name='int'),
-                 ),
-                 doc='number of non-zeros in constraint Jacobian row T',
-                 array_extent=('nidof',),
-             ),
-             StructFieldDecl(
-                 name='iefc_JT_rowadr',
-                 type=PointerType(
-                     inner_type=ValueType(name='int'),
-                 ),
-                 doc='row start address in colind array              T',
-                 array_extent=('nidof',),
-             ),
-             StructFieldDecl(
-                 name='iefc_JT_rowsuper',
-                 type=PointerType(
-                     inner_type=ValueType(name='int'),
-                 ),
-                 doc='number of subsequent rows in supernode         T',
-                 array_extent=('nidof',),
-             ),
-             StructFieldDecl(
-                 name='iefc_JT_colind',
-                 type=PointerType(
-                     inner_type=ValueType(name='int'),
-                 ),
-                 doc='column indices in constraint Jacobian          T',
-                 array_extent=('nJ',),
-             ),
              StructFieldDecl(
                  name='iefc_J',
                  type=PointerType(
@@ -6290,14 +6218,6 @@ STRUCTS: Mapping[str, StructDecl] = dict([
                  doc='constraint Jacobian',
                  array_extent=('nJ',),
              ),
-             StructFieldDecl(
-                 name='iefc_JT',
-                 type=PointerType(
-                     inner_type=ValueType(name='mjtNum'),
-                 ),
-                 doc='constraint Jacobian transposed',
-                 array_extent=('nJ',),
-             ),
              StructFieldDecl(
                  name='iefc_frictionloss',
                  type=PointerType(

src/engine/engine_core_constraint.c

@@ -386,10 +386,10 @@ void mj_mulJacTVec(const mjModel* m, const mjData* d, mjtNum* res, const mjtNum*
   }
 
   // sparse Jacobian
-  if (mj_isSparse(m))
+  if (mj_isSparse(m)) {
-    mju_mulMatVecSparse(res, d->efc_JT, vec, m->nv,
+    mju_mulMatTVecSparse(res, d->efc_J, vec, d->nefc, m->nv,
-                        d->efc_JT_rownnz, d->efc_JT_rowadr,
+                        d->efc_J_rownnz, d->efc_J_rowadr, d->efc_J_colind);
-                        d->efc_JT_colind, d->efc_JT_rowsuper);
+  }
 
   // dense Jacobian
   else {
@@ -1996,12 +1996,6 @@ void mj_makeConstraint(const mjModel* m, mjData* d) {
 
   // transpose sparse Jacobian, make row supernodes
   if (mj_isSparse(m)) {
-    // transpose
-    mju_transposeSparse(d->efc_JT, d->efc_J, d->nefc, m->nv,
-                        d->efc_JT_rownnz, d->efc_JT_rowadr, d->efc_JT_colind, d->efc_JT_rowsuper,
-                        d->efc_J_rownnz, d->efc_J_rowadr, d->efc_J_colind);
-
-
 #ifdef mjUSEAVX
     // compute supernodes of J; used by mju_mulMatVecSparse_avx
     mju_superSparse(d->nefc, d->efc_J_rowsuper,

src/engine/engine_island.c

@@ -597,20 +597,6 @@ void mj_island(const mjModel* m, mjData* d) {
       mju_superSparse(d->island_nefc[island], d->iefc_J_rowsuper + adr,
                       d->iefc_J_rownnz + adr, d->iefc_J_rowadr + adr, d->iefc_J_colind);
     }
-
-    // block-diagonalize Jacobian-transpose
-    mju_blockDiagSparse(d->iefc_JT, d->iefc_JT_rownnz, d->iefc_JT_rowadr, d->iefc_JT_colind,
-                        d->efc_JT, d->efc_JT_rownnz, d->efc_JT_rowadr, d->efc_JT_colind,
-                        nidof, nisland,
-                        d->map_idof2dof, d->map_efc2iefc,
-                        d->island_idofadr, d->island_iefcadr, NULL, NULL);
-
-    // recompute rowsuper per island
-    for (int island=0; island < nisland; island++) {
-      int adr = d->island_idofadr[island];
-      mju_superSparse(d->island_nv[island], d->iefc_JT_rowsuper + adr,
-                      d->iefc_JT_rownnz + adr, d->iefc_JT_rowadr + adr, d->iefc_JT_colind);
-    }
   }
 
   // copy position-dependent efc vectors required by solver

src/engine/engine_print.c

@@ -1236,8 +1236,6 @@ void mj_printFormattedData(const mjModel* m, const mjData* d, const char* filena
     printArrayInt("EFC_J_ROWADR", d->nefc, 1, d->efc_J_rowadr, fp);
     printSparse("EFC_J", d->efc_J, d->nefc, d->efc_J_rownnz,
                 d->efc_J_rowadr, d->efc_J_colind, fp, float_format);
-    mj_printSparsity("JT: constraint Jacobian transposed", m->nv, d->nefc, d->efc_JT_rowadr, NULL,
-                     d->efc_JT_rownnz, d->efc_JT_rowsuper, d->efc_JT_colind, fp);
     if (mj_isDual(m)) {
       printArrayInt("EFC_AR_ROWNNZ", d->nefc, 1, d->efc_AR_rownnz, fp);
       printArrayInt("EFC_AR_ROWADR", d->nefc, 1, d->efc_AR_rowadr, fp);

test/benchmark/engine_util_sparse_benchmark_test.cc

@@ -448,14 +448,23 @@ static void BM_combineSparse(benchmark::State& state, CombineFuncPtr func) {
     }
   }
 
+  int* JT_rownnz   = mj_stackAllocInt(d, m->nv);
+  int* JT_rowadr   = mj_stackAllocInt(d, m->nv);
+  int* JT_rowsuper = mj_stackAllocInt(d, m->nv);
+  int* JT_colind   = mj_stackAllocInt(d, d->nJ);
+  mjtNum* JT       = mj_stackAllocNum(d, d->nJ);
+  mju_transposeSparse(JT, d->efc_J, d->nefc, m->nv,
+                      JT_rownnz, JT_rowadr, JT_colind, JT_rowsuper,
+                      d->efc_J_rownnz, d->efc_J_rowadr, d->efc_J_colind);
+
   // compute H = J'*D*J, uncompressed layout
   mju_sqrMatTDUncompressedInit(rowadr, m->nv);
-  mju_sqrMatTDSparse(H, d->efc_J, d->efc_JT, D, d->nefc, m->nv,
+  mju_sqrMatTDSparse(H, d->efc_J, JT, D, d->nefc, m->nv,
                      rownnz, rowadr, colind,
                      d->efc_J_rownnz, d->efc_J_rowadr,
                      d->efc_J_colind, d->efc_J_rowsuper,
-                     d->efc_JT_rownnz, d->efc_JT_rowadr,
+                     JT_rownnz, JT_rowadr,
-                     d->efc_JT_colind, d->efc_JT_rowsuper, d,
+                     JT_colind, JT_rowsuper, d,
                      diagind);
 
   // compute H = M + J'*D*J
@@ -605,19 +614,28 @@ static void BM_sqrMatTDSparse(benchmark::State& state, SqrMatTDFuncPtr func) {
     }
   }
 
+  int* JT_rownnz   = mj_stackAllocInt(d, m->nv);
+  int* JT_rowadr   = mj_stackAllocInt(d, m->nv);
+  int* JT_rowsuper = mj_stackAllocInt(d, m->nv);
+  int* JT_colind   = mj_stackAllocInt(d, d->nJ);
+  mjtNum* JT       = mj_stackAllocNum(d, d->nJ);
+  mju_transposeSparse(JT, d->efc_J, d->nefc, m->nv,
+                      JT_rownnz, JT_rowadr, JT_colind, JT_rowsuper,
+                      d->efc_J_rownnz, d->efc_J_rowadr, d->efc_J_colind);
+
   // time benchmark
   if (func) {
     mju_sqrMatTDSparseCount(rownnz, rowadr, m->nv,
       d->efc_J_rownnz, d->efc_J_rowadr, d->efc_J_colind,
-      d->efc_JT_rownnz, d->efc_JT_rowadr,
+      JT_rownnz, JT_rowadr,
-      d->efc_JT_colind, nullptr, d, 1);
+      JT_colind, nullptr, d, 1);
 
     for (auto s : state) {
       // compute H = J'*D*J, compressed layout
-      func(H, d->efc_J, d->efc_JT, D, d->nefc, m->nv, rownnz, rowadr, colind,
+      func(H, d->efc_J, JT, D, d->nefc, m->nv, rownnz, rowadr, colind,
          d->efc_J_rownnz, d->efc_J_rowadr, d->efc_J_colind, NULL,
-         d->efc_JT_rownnz, d->efc_JT_rowadr, d->efc_JT_colind,
+         JT_rownnz, JT_rowadr, JT_colind,
-         d->efc_JT_rowsuper, d, diagind);
+         JT_rowsuper, d, diagind);
     }
   } else {
     for (auto s : state) {
@@ -627,10 +645,10 @@ static void BM_sqrMatTDSparse(benchmark::State& state, SqrMatTDFuncPtr func) {
 
       // compute H = J'*D*J, uncompressed layout
       mju_sqrMatTDSparse_baseline(
-          H, d->efc_J, d->efc_JT, D, d->nefc, m->nv, rownnz, rowadr, colind,
+          H, d->efc_J, JT, D, d->nefc, m->nv, rownnz, rowadr, colind,
           d->efc_J_rownnz, d->efc_J_rowadr, d->efc_J_colind, d->efc_J_rowsuper,
-          d->efc_JT_rownnz, d->efc_JT_rowadr, d->efc_JT_colind,
+          JT_rownnz, JT_rowadr, JT_colind,
-          d->efc_JT_rowsuper, d, /*unused=*/nullptr);
+          JT_rowsuper, d, /*unused=*/nullptr);
     }
   }
 

test/engine/engine_island_test.cc

@@ -467,27 +467,6 @@ TEST_F(IslandTest, IslandJacobian) {
               EXPECT_EQ(J_island[i * nv_island + j], J[efc * nv + dof]);
             }
           }
-
-          // === test JT (if sparse)
-
-          // get pointer to J_island, dense (nefc_island x nv_island) submatrix
-          if (jac == mjJAC_SPARSE) {
-            // dense copy of island in iJ (here used as scratch)
-            mju_sparse2dense(iJ, d->iefc_JT, nv_island, nefc_island,
-                             d->iefc_JT_rownnz + idof,
-                             d->iefc_JT_rowadr + idof,
-                             d->iefc_JT_colind);
-            J_island = iJ;
-
-            // sequential memory in J_island equals random access memory in J
-            for (int i=0; i < nv_island; i++) {
-              for (int j=0; j < nefc_island; j++) {
-                int dof = d->map_idof2dof[idof + i];
-                int efc = d->map_iefc2efc[iefc + j];
-                EXPECT_EQ(J_island[i * nefc_island + j], J[efc * nv + dof]);
-              }
-            }
-          }
         }
 
         mju_free(iJ);

unity/Runtime/Bindings/MjBindings.cs

@@ -5001,12 +5001,7 @@ public unsafe struct mjData_ {
   public int* efc_J_rowadr;
   public int* efc_J_rowsuper;
   public int* efc_J_colind;
-  public int* efc_JT_rownnz;
-  public int* efc_JT_rowadr;
-  public int* efc_JT_rowsuper;
-  public int* efc_JT_colind;
   public double* efc_J;
-  public double* efc_JT;
   public double* efc_pos;
   public double* efc_margin;
   public double* efc_frictionloss;
@@ -5043,12 +5038,7 @@ public unsafe struct mjData_ {
   public int* iefc_J_rowadr;
   public int* iefc_J_rowsuper;
   public int* iefc_J_colind;
-  public int* iefc_JT_rownnz;
-  public int* iefc_JT_rowadr;
-  public int* iefc_JT_rowsuper;
-  public int* iefc_JT_colind;
   public double* iefc_J;
-  public double* iefc_JT;
   public double* iefc_frictionloss;
   public double* iefc_D;
   public double* iefc_R;