1: /*
  2:    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
  3:    SLEPc - Scalable Library for Eigenvalue Problem Computations
  4:    Copyright (c) 2002-, Universitat Politecnica de Valencia, Spain

  6:    This file is part of SLEPc.
  7:    SLEPc is distributed under a 2-clause BSD license (see LICENSE).
  8:    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
  9: */

 11: static char help[] = "Test logarithm function.\n\n";

 13: #include <slepcfn.h>

 15: int main(int argc,char **argv)
 16: {
 17:   FN             fn;
 18:   PetscScalar    x,y,yp,tau,eta;
 19:   char           strx[50],str[50];

 21:   PetscFunctionBeginUser;
 22:   PetscCall(SlepcInitialize(&argc,&argv,(char*)0,help));
 23:   PetscCall(FNCreate(PETSC_COMM_WORLD,&fn));

 25:   /* plain logarithm log(x) */
 26:   PetscCall(FNSetType(fn,FNLOG));
 27:   PetscCall(FNView(fn,NULL));
 28:   x = 2.2;
 29:   PetscCall(SlepcSNPrintfScalar(strx,sizeof(strx),x,PETSC_FALSE));
 30:   PetscCall(FNEvaluateFunction(fn,x,&y));
 31:   PetscCall(FNEvaluateDerivative(fn,x,&yp));
 32:   PetscCall(SlepcSNPrintfScalar(str,sizeof(str),y,PETSC_FALSE));
 33:   PetscCall(PetscPrintf(PETSC_COMM_WORLD,"  f(%s)=%s\n",strx,str));
 34:   PetscCall(SlepcSNPrintfScalar(str,sizeof(str),yp,PETSC_FALSE));
 35:   PetscCall(PetscPrintf(PETSC_COMM_WORLD,"  f'(%s)=%s\n",strx,str));

 37:   /* logarithm with scaling factors eta*log(tau*x) */
 38:   PetscCall(FNSetType(fn,FNLOG));
 39:   tau = 0.2;
 40:   eta = 1.3;
 41:   PetscCall(FNSetScale(fn,tau,eta));
 42:   PetscCall(FNView(fn,NULL));
 43:   x = 2.2;
 44:   PetscCall(SlepcSNPrintfScalar(strx,sizeof(strx),x,PETSC_FALSE));
 45:   PetscCall(FNEvaluateFunction(fn,x,&y));
 46:   PetscCall(FNEvaluateDerivative(fn,x,&yp));
 47:   PetscCall(SlepcSNPrintfScalar(str,sizeof(str),y,PETSC_FALSE));
 48:   PetscCall(PetscPrintf(PETSC_COMM_WORLD,"  f(%s)=%s\n",strx,str));
 49:   PetscCall(SlepcSNPrintfScalar(str,sizeof(str),yp,PETSC_FALSE));
 50:   PetscCall(PetscPrintf(PETSC_COMM_WORLD,"  f'(%s)=%s\n",strx,str));

 52:   PetscCall(FNDestroy(&fn));
 53:   PetscCall(SlepcFinalize());
 54:   return 0;
 55: }

 57: /*TEST

 59:    test:
 60:       suffix: 1
 61:       nsize: 1
 62:       filter: grep -v "computing matrix functions"

 64: TEST*/