static char help[] = "Tests MatShift(), MatScale(), and MatDiagonalScale() for SHELL and NEST matrices\n\n";

#include <petscmat.h>

typedef struct _n_User *User;
struct _n_User {
  Mat B;
};

static PetscErrorCode MatView_User(Mat A, PetscViewer viewer) {
  User user;

  PetscFunctionBegin;
  PetscCall(MatShellGetContext(A, &user));
  PetscCall(MatView(user->B, viewer));
  PetscFunctionReturn(0);
}

static PetscErrorCode MatMult_User(Mat A, Vec X, Vec Y) {
  User user;

  PetscFunctionBegin;
  PetscCall(MatShellGetContext(A, &user));
  PetscCall(MatMult(user->B, X, Y));
  PetscFunctionReturn(0);
}

static PetscErrorCode MatMultTranspose_User(Mat A, Vec X, Vec Y) {
  User user;

  PetscFunctionBegin;
  PetscCall(MatShellGetContext(A, &user));
  PetscCall(MatMultTranspose(user->B, X, Y));
  PetscFunctionReturn(0);
}

static PetscErrorCode MatGetDiagonal_User(Mat A, Vec X) {
  User user;

  PetscFunctionBegin;
  PetscCall(MatShellGetContext(A, &user));
  PetscCall(MatGetDiagonal(user->B, X));
  PetscFunctionReturn(0);
}

static PetscErrorCode TestMatrix(Mat A, Vec X, Vec Y, Vec Z) {
  Vec         W1, W2, diff;
  Mat         E;
  const char *mattypename;
  PetscViewer viewer      = PETSC_VIEWER_STDOUT_WORLD;
  PetscScalar diag[2]     = {2.9678190300000000e+08, 1.4173141580000000e+09};
  PetscScalar multadd[2]  = {-6.8966198500000000e+08, -2.0310609940000000e+09};
  PetscScalar multtadd[2] = {-9.1052873900000000e+08, -1.8101942400000000e+09};
  PetscReal   nrm;

  PetscFunctionBegin;
  PetscCall(PetscObjectGetType((PetscObject)A, &mattypename));
  PetscCall(PetscViewerASCIIPrintf(viewer, "\nMatrix of type: %s\n", mattypename));
  PetscCall(VecDuplicate(X, &W1));
  PetscCall(VecDuplicate(X, &W2));
  PetscCall(MatScale(A, 31));
  PetscCall(MatShift(A, 37));
  PetscCall(MatDiagonalScale(A, X, Y));
  PetscCall(MatScale(A, 41));
  PetscCall(MatDiagonalScale(A, Y, Z));
  PetscCall(MatComputeOperator(A, MATDENSE, &E));

  PetscCall(MatView(E, viewer));
  PetscCall(PetscViewerASCIIPrintf(viewer, "Testing MatMult + MatMultTranspose\n"));
  PetscCall(MatMult(A, Z, W1));
  PetscCall(MatMultTranspose(A, W1, W2));
  PetscCall(VecView(W2, viewer));

  PetscCall(PetscViewerASCIIPrintf(viewer, "Testing MatMultAdd\n"));
  PetscCall(VecCreateSeqWithArray(PETSC_COMM_SELF, 1, 2, multadd, &diff));
  PetscCall(VecSet(W1, -1.0));
  PetscCall(MatMultAdd(A, W1, W1, W2));
  PetscCall(VecView(W2, viewer));
  PetscCall(VecAXPY(W2, -1.0, diff));
  PetscCall(VecNorm(W2, NORM_2, &nrm));
#if defined(PETSC_USE_REAL_DOUBLE) || defined(PETSC_USE_REAL___FLOAT128)
  PetscCheck(nrm <= PETSC_SMALL, PETSC_COMM_SELF, PETSC_ERR_PLIB, "MatMultAdd(A,x,x,y) produces incorrect result");
#endif

  PetscCall(VecSet(W2, -1.0));
  PetscCall(MatMultAdd(A, W1, W2, W2));
  PetscCall(VecView(W2, viewer));
  PetscCall(VecAXPY(W2, -1.0, diff));
  PetscCall(VecNorm(W2, NORM_2, &nrm));
#if defined(PETSC_USE_REAL_DOUBLE) || defined(PETSC_USE_REAL___FLOAT128)
  PetscCheck(nrm <= PETSC_SMALL, PETSC_COMM_SELF, PETSC_ERR_PLIB, "MatMultAdd(A,x,y,y) produces incorrect result");
#endif
  PetscCall(VecDestroy(&diff));

  PetscCall(PetscViewerASCIIPrintf(viewer, "Testing MatMultTransposeAdd\n"));
  PetscCall(VecCreateSeqWithArray(PETSC_COMM_SELF, 1, 2, multtadd, &diff));

  PetscCall(VecSet(W1, -1.0));
  PetscCall(MatMultTransposeAdd(A, W1, W1, W2));
  PetscCall(VecView(W2, viewer));
  PetscCall(VecAXPY(W2, -1.0, diff));
  PetscCall(VecNorm(W2, NORM_2, &nrm));
#if defined(PETSC_USE_REAL_DOUBLE) || defined(PETSC_USE_REAL___FLOAT128)
  PetscCheck(nrm <= PETSC_SMALL, PETSC_COMM_SELF, PETSC_ERR_PLIB, "MatMultTransposeAdd(A,x,x,y) produces incorrect result");
#endif

  PetscCall(VecSet(W2, -1.0));
  PetscCall(MatMultTransposeAdd(A, W1, W2, W2));
  PetscCall(VecView(W2, viewer));
  PetscCall(VecAXPY(W2, -1.0, diff));
  PetscCall(VecNorm(W2, NORM_2, &nrm));
#if defined(PETSC_USE_REAL_DOUBLE) || defined(PETSC_USE_REAL___FLOAT128)
  PetscCheck(nrm <= PETSC_SMALL, PETSC_COMM_SELF, PETSC_ERR_PLIB, "MatMultTransposeAdd(A,x,y,y) produces incorrect result");
#endif
  PetscCall(VecDestroy(&diff));

  PetscCall(PetscViewerASCIIPrintf(viewer, "Testing MatGetDiagonal\n"));
  PetscCall(MatGetDiagonal(A, W2));
  PetscCall(VecView(W2, viewer));
  PetscCall(VecCreateSeqWithArray(PETSC_COMM_SELF, 1, 2, diag, &diff));
  PetscCall(VecAXPY(diff, -1.0, W2));
  PetscCall(VecNorm(diff, NORM_2, &nrm));
  PetscCheck(nrm <= PETSC_SMALL, PETSC_COMM_SELF, PETSC_ERR_PLIB, "MatGetDiagonal() produces incorrect result");
  PetscCall(VecDestroy(&diff));

  /* MATSHELL does not support MatDiagonalSet after MatScale */
  if (strncmp(mattypename, "shell", 5)) {
    PetscCall(MatDiagonalSet(A, X, INSERT_VALUES));
    PetscCall(MatGetDiagonal(A, W1));
    PetscCall(VecView(W1, viewer));
  } else {
    PetscCall(PetscViewerASCIIPrintf(viewer, "MatDiagonalSet not tested on MATSHELL\n"));
  }

  PetscCall(MatDestroy(&E));
  PetscCall(VecDestroy(&W1));
  PetscCall(VecDestroy(&W2));
  PetscFunctionReturn(0);
}

int main(int argc, char **args) {
  const PetscScalar xvals[] = {11, 13}, yvals[] = {17, 19}, zvals[] = {23, 29};
  const PetscInt    inds[]  = {0, 1};
  PetscScalar       avals[] = {2, 3, 5, 7};
  Mat               A, S, D[4], N;
  Vec               X, Y, Z;
  User              user;
  PetscInt          i;

  PetscFunctionBeginUser;
  PetscCall(PetscInitialize(&argc, &args, (char *)0, help));
  PetscCall(MatCreateSeqAIJ(PETSC_COMM_WORLD, 2, 2, 2, NULL, &A));
  PetscCall(MatSetUp(A));
  PetscCall(MatSetValues(A, 2, inds, 2, inds, avals, INSERT_VALUES));
  PetscCall(VecCreateSeq(PETSC_COMM_WORLD, 2, &X));
  PetscCall(VecDuplicate(X, &Y));
  PetscCall(VecDuplicate(X, &Z));
  PetscCall(VecSetValues(X, 2, inds, xvals, INSERT_VALUES));
  PetscCall(VecSetValues(Y, 2, inds, yvals, INSERT_VALUES));
  PetscCall(VecSetValues(Z, 2, inds, zvals, INSERT_VALUES));
  PetscCall(MatAssemblyBegin(A, MAT_FINAL_ASSEMBLY));
  PetscCall(MatAssemblyEnd(A, MAT_FINAL_ASSEMBLY));
  PetscCall(VecAssemblyBegin(X));
  PetscCall(VecAssemblyBegin(Y));
  PetscCall(VecAssemblyBegin(Z));
  PetscCall(VecAssemblyEnd(X));
  PetscCall(VecAssemblyEnd(Y));
  PetscCall(VecAssemblyEnd(Z));

  PetscCall(PetscNew(&user));
  user->B = A;

  PetscCall(MatCreateShell(PETSC_COMM_WORLD, 2, 2, 2, 2, user, &S));
  PetscCall(MatSetUp(S));
  PetscCall(MatShellSetOperation(S, MATOP_VIEW, (void (*)(void))MatView_User));
  PetscCall(MatShellSetOperation(S, MATOP_MULT, (void (*)(void))MatMult_User));
  PetscCall(MatShellSetOperation(S, MATOP_MULT_TRANSPOSE, (void (*)(void))MatMultTranspose_User));
  PetscCall(MatShellSetOperation(S, MATOP_GET_DIAGONAL, (void (*)(void))MatGetDiagonal_User));

  for (i = 0; i < 4; i++) { PetscCall(MatCreateSeqDense(PETSC_COMM_WORLD, 1, 1, &avals[i], &D[i])); }
  PetscCall(MatCreateNest(PETSC_COMM_WORLD, 2, NULL, 2, NULL, D, &N));
  PetscCall(MatSetUp(N));

  PetscCall(TestMatrix(S, X, Y, Z));
  PetscCall(TestMatrix(A, X, Y, Z));
  PetscCall(TestMatrix(N, X, Y, Z));

  for (i = 0; i < 4; i++) PetscCall(MatDestroy(&D[i]));
  PetscCall(MatDestroy(&A));
  PetscCall(MatDestroy(&S));
  PetscCall(MatDestroy(&N));
  PetscCall(VecDestroy(&X));
  PetscCall(VecDestroy(&Y));
  PetscCall(VecDestroy(&Z));
  PetscCall(PetscFree(user));
  PetscCall(PetscFinalize());
  return 0;
}

/*TEST

   test:

TEST*/