Date: 2021-09-20T09:44:15+00:00

Actual source code: slepcmath.h
slepc-3.15.2 2021-09-20
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      1: /*
      2:    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
      3:    SLEPc - Scalable Library for Eigenvalue Problem Computations
      4:    Copyright (c) 2002-2021, 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: */
     10: /*
     11:    SLEPc mathematics include file. Defines basic operations and functions.
     12:    This file is included by slepcsys.h and should not be used directly.
     13: */

     15: #if !defined(SLEPCMATH_H)
     16: #define SLEPCMATH_H

     18: /*
     19:     Default tolerance for the different solvers, depending on the precision
     20: */
     21: #if defined(PETSC_USE_REAL_SINGLE)
     22: #  define SLEPC_DEFAULT_TOL   1e-5
     23: #elif defined(PETSC_USE_REAL_DOUBLE)
     24: #  define SLEPC_DEFAULT_TOL   1e-8
     25: #elif defined(PETSC_USE_REAL___FLOAT128)
     26: #  define SLEPC_DEFAULT_TOL   1e-16
     27: #elif defined(PETSC_USE_REAL___FP16)
     28: #  define SLEPC_DEFAULT_TOL   1e-2
     29: #endif

     31: /*@C
     32:    SlepcAbs - Returns sqrt(x**2+y**2), taking care not to cause unnecessary
     33:    overflow. It is based on LAPACK's DLAPY2.

     35:    Not Collective

     37:    Input parameters:
     38: .  x,y - the real numbers

     40:    Output parameter:
     41: .  return - the result

     43:    Note:
     44:    This function is not available from Fortran.

     46:    Level: developer
     47: @*/
     48: PETSC_STATIC_INLINE PetscReal SlepcAbs(PetscReal x,PetscReal y)
     49: {
     50:   PetscReal w,z,t,xabs=PetscAbs(x),yabs=PetscAbs(y);

     52:   w = PetscMax(xabs,yabs);
     53:   z = PetscMin(xabs,yabs);
     54:   if (z == 0.0) return w;
     55:   t = z/w;
     56:   return w*PetscSqrtReal(1.0+t*t);
     57: }

     59: /*MC
     60:    SlepcAbsEigenvalue - Returns the absolute value of a complex number given
     61:    its real and imaginary parts.

     63:    Synopsis:
     64:    PetscReal SlepcAbsEigenvalue(PetscScalar x,PetscScalar y)

     66:    Not Collective

     68:    Input parameters:
     69: +  x  - the real part of the complex number
     70: -  y  - the imaginary part of the complex number

     72:    Notes:
     73:    This function computes sqrt(x**2+y**2), taking care not to cause unnecessary
     74:    overflow. It is based on LAPACK's DLAPY2.

     76:    This function is not available from Fortran.

     78:    Level: developer
     79: M*/
     80: #if !defined(PETSC_USE_COMPLEX)
     81: #define SlepcAbsEigenvalue(x,y) SlepcAbs(x,y)
     82: #else
     83: #define SlepcAbsEigenvalue(x,y) PetscAbsScalar(x)
     84: #endif

     86: #endif

     89: /*
     90:    SlepcSetFlushToZero - Set the FTZ flag in floating-point arithmetic.
     91: */
     92: PETSC_STATIC_INLINE PetscErrorCode SlepcSetFlushToZero(unsigned int *state)
     93: {
     95: #if defined(PETSC_HAVE_XMMINTRIN_H)
     96: #if defined(_MM_FLUSH_ZERO_ON) && defined(__SSE__)
     97:   *state = _MM_GET_FLUSH_ZERO_MODE();
     98:   _MM_SET_FLUSH_ZERO_MODE(_MM_FLUSH_ZERO_ON);
     99: #else
    100:   *state = 0;
    101: #endif
    102: #endif
    103:   return(0);
    104: }

    106: /*
    107:    SlepcResetFlushToZero - Reset the FTZ flag in floating-point arithmetic.
    108: */
    109: PETSC_STATIC_INLINE PetscErrorCode SlepcResetFlushToZero(unsigned int *state)
    110: {
    112: #if defined(PETSC_HAVE_XMMINTRIN_H)
    113: #if defined(_MM_FLUSH_ZERO_MASK) && defined(__SSE__)
    114:   _MM_SET_FLUSH_ZERO_MODE(*state & _MM_FLUSH_ZERO_MASK);
    115: #endif
    116: #endif
    117:   return(0);
    118: }