Actual source code: ex2.c

  1: /*
  2:  * Example code testing SeqDense matrices with an LDA (leading dimension
  3:  * of the user-allocated arrray) larger than M.
  4:  * This example tests the functionality of MatInsertValues, MatMult,
  5:  * and MatMultTranspose.
  6:  */
  7: #include <stdlib.h>
 8:  #include petscmat.h

 12: int main(int argc,char **argv)
 13: {
 14:   Mat            A,A11,A12,A21,A22;
 15:   Vec            X,X1,X2,Y,Z,Z1,Z2;
 16:   PetscScalar    *a,*b,*x,*y,*z,v,one=1,mone=-1;
 17:   PetscReal      nrm;
 19:   PetscInt       size=8,size1=6,size2=2, i,j;

 21:   PetscInitialize(&argc,&argv,0,0);

 23:   /*
 24:    * Create matrix and three vectors: these are all normal
 25:    */
 26:   PetscMalloc(size*size*sizeof(PetscScalar),&a);
 27:   PetscMalloc(size*size*sizeof(PetscScalar),&b);
 28:   for (i=0; i<size; i++) {
 29:     for (j=0; j<size; j++) {
 30:       a[i+j*size] = rand(); b[i+j*size] = a[i+j*size];
 31:     }
 32:   }
 33:   MatCreate(MPI_COMM_SELF,size,size,size,size,&A);
 34:   MatSetType(A,MATSEQDENSE);
 35:   MatSeqDenseSetPreallocation(A,a);
 36:   MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);
 37:   MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);

 39:   PetscMalloc(size*sizeof(PetscScalar),&x);
 40:   for (i=0; i<size; i++) {
 41:     x[i] = one;
 42:   }
 43:   VecCreateSeqWithArray(MPI_COMM_SELF,size,x,&X);
 44:   VecAssemblyBegin(X);
 45:   VecAssemblyEnd(X);

 47:   PetscMalloc(size*sizeof(PetscScalar),&y);
 48:   VecCreateSeqWithArray(MPI_COMM_SELF,size,y,&Y);
 49:   VecAssemblyBegin(Y);
 50:   VecAssemblyEnd(Y);

 52:   PetscMalloc(size*sizeof(PetscScalar),&z);
 53:   VecCreateSeqWithArray(MPI_COMM_SELF,size,z,&Z);
 54:   VecAssemblyBegin(Z);
 55:   VecAssemblyEnd(Z);

 57:   /*
 58:    * Now create submatrices and subvectors
 59:    */
 60:   MatCreate(MPI_COMM_SELF,size1,size1,size1,size1,&A11);
 61:   MatSetType(A11,MATSEQDENSE);
 62:   MatSeqDenseSetPreallocation(A11,b);
 63:   MatSeqDenseSetLDA(A11,size);
 64:   MatAssemblyBegin(A11,MAT_FINAL_ASSEMBLY);
 65:   MatAssemblyEnd(A11,MAT_FINAL_ASSEMBLY);

 67:   MatCreate(MPI_COMM_SELF,size1,size2,size1,size2,&A12);
 68:   MatSetType(A12,MATSEQDENSE);
 69:   MatSeqDenseSetPreallocation(A12,b+size1*size);
 70:   MatSeqDenseSetLDA(A12,size);
 71:   MatAssemblyBegin(A12,MAT_FINAL_ASSEMBLY);
 72:   MatAssemblyEnd(A12,MAT_FINAL_ASSEMBLY);

 74:   MatCreate(MPI_COMM_SELF,size2,size1,size2,size1,&A21);
 75:   MatSetType(A21,MATSEQDENSE);
 76:   MatSeqDenseSetPreallocation(A21,b+size1);
 77:   MatSeqDenseSetLDA(A21,size);
 78:   MatAssemblyBegin(A21,MAT_FINAL_ASSEMBLY);
 79:   MatAssemblyEnd(A21,MAT_FINAL_ASSEMBLY);

 81:   MatCreate(MPI_COMM_SELF,size2,size2,size2,size2,&A22);
 82:   MatSetType(A22,MATSEQDENSE);
 83:   MatSeqDenseSetPreallocation(A22,b+size1*size+size1);
 84:   MatSeqDenseSetLDA(A22,size);
 85:   MatAssemblyBegin(A22,MAT_FINAL_ASSEMBLY);
 86:   MatAssemblyEnd(A22,MAT_FINAL_ASSEMBLY);

 88:   VecCreateSeqWithArray(MPI_COMM_SELF,size1,x,&X1);
 89:   VecCreateSeqWithArray(MPI_COMM_SELF,size2,x+size1,&X2);
 90:   VecCreateSeqWithArray(MPI_COMM_SELF,size1,z,&Z1);
 91:   VecCreateSeqWithArray(MPI_COMM_SELF,size2,z+size1,&Z2);

 93:   /*
 94:    * Now multiple matrix times input in two ways;
 95:    * compare the results
 96:    */
 97:   MatMult(A,X,Y);
 98:   MatMult(A11,X1,Z1);
 99:   MatMultAdd(A12,X2,Z1,Z1);
100:   MatMult(A22,X2,Z2);
101:   MatMultAdd(A21,X1,Z2,Z2);
102:   VecAXPY(&mone,Y,Z);
103:   VecNorm(Z,NORM_2,&nrm);
104:   printf("Test1; error norm=%e\n",nrm);
105:   /*
106:   printf("MatMult the usual way:\n"); VecView(Y,0);
107:   printf("MatMult by subblock:\n"); VecView(Z,0);
108:   */

110:   /*
111:    * Next test: change both matrices
112:    */
113:   v = rand(); i=1; j=size-2;
114:   MatSetValues(A,1,&i,1,&j,&v,INSERT_VALUES);
115:   j -= size1;
116:   MatSetValues(A12,1,&i,1,&j,&v,INSERT_VALUES);
117:   v = rand(); i=j=size1+1;
118:   MatSetValues(A,1,&i,1,&j,&v,INSERT_VALUES);
119:   i=j=1;
120:   MatSetValues(A22,1,&i,1,&j,&v,INSERT_VALUES);
121:   MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY);
122:   MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY);
123:   MatAssemblyBegin(A12,MAT_FINAL_ASSEMBLY);
124:   MatAssemblyEnd(A12,MAT_FINAL_ASSEMBLY);
125:   MatAssemblyBegin(A22,MAT_FINAL_ASSEMBLY);
126:   MatAssemblyEnd(A22,MAT_FINAL_ASSEMBLY);

128:   MatMult(A,X,Y);
129:   MatMult(A11,X1,Z1);
130:   MatMultAdd(A12,X2,Z1,Z1);
131:   MatMult(A22,X2,Z2);
132:   MatMultAdd(A21,X1,Z2,Z2);
133:   VecAXPY(&mone,Y,Z);
134:   VecNorm(Z,NORM_2,&nrm);
135:   printf("Test2; error norm=%e\n",nrm);

137:   /*
138:    * Transpose product
139:    */
140:   MatMultTranspose(A,X,Y);
141:   MatMultTranspose(A11,X1,Z1);
142:   MatMultTransposeAdd(A21,X2,Z1,Z1);
143:   MatMultTranspose(A22,X2,Z2);
144:   MatMultTransposeAdd(A12,X1,Z2,Z2);
145:   VecAXPY(&mone,Y,Z);
146:   VecNorm(Z,NORM_2,&nrm);
147:   printf("Test3; error norm=%e\n",nrm);

149:   PetscFinalize();
150:   return 0;
151: }