Actual source code: slepcmath.h
slepc-3.21.1 2024-04-26
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      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: */
     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: #pragma once

     17: /* SUBMANSEC = sys */

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

     32: static inline PetscReal SlepcDefaultTol(PetscReal tol)
     33: {
     34:   return tol == (PetscReal)PETSC_DEFAULT ? SLEPC_DEFAULT_TOL : tol;
     35: }

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

     41:    Not Collective

     43:    Input parameters:
     44: .  x,y - the real numbers

     46:    Output parameter:
     47: .  return - the result

     49:    Note:
     50:    This function is not available from Fortran.

     52:    Level: developer
     53: @*/
     54: static inline PetscReal SlepcAbs(PetscReal x,PetscReal y)
     55: {
     56:   PetscReal w,z,t,xabs=PetscAbs(x),yabs=PetscAbs(y);

     58:   w = PetscMax(xabs,yabs);
     59:   z = PetscMin(xabs,yabs);
     60:   if (PetscUnlikely(z == (PetscReal)0.0)) return w;
     61:   t = z/w;
     62:   return w*PetscSqrtReal((PetscReal)1.0+t*t);
     63: }

     65: /*MC
     66:    SlepcAbsEigenvalue - Returns the absolute value of a complex number given
     67:    its real and imaginary parts.

     69:    Synopsis:
     70:    PetscReal SlepcAbsEigenvalue(PetscScalar x,PetscScalar y)

     72:    Not Collective

     74:    Input parameters:
     75: +  x  - the real part of the complex number
     76: -  y  - the imaginary part of the complex number

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

     82:    In complex scalars, only the first argument is used.

     84:    This function is not available from Fortran.

     86:    Level: developer
     87: M*/
     88: #if !defined(PETSC_USE_COMPLEX)
     89: #define SlepcAbsEigenvalue(x,y) SlepcAbs(x,y)
     90: #else
     91: #define SlepcAbsEigenvalue(x,y) PetscAbsScalar(x)
     92: #endif

     94: /*
     95:    SlepcSetFlushToZero - Set the FTZ flag in floating-point arithmetic.
     96: */
     97: static inline PetscErrorCode SlepcSetFlushToZero(unsigned int *state)
     98: {
     99:   PetscFunctionBegin;
    100: #if defined(PETSC_HAVE_XMMINTRIN_H) && defined(_MM_FLUSH_ZERO_ON) && defined(__SSE__)
    101:   *state = _MM_GET_FLUSH_ZERO_MODE();
    102:   _MM_SET_FLUSH_ZERO_MODE(_MM_FLUSH_ZERO_ON);
    103: #else
    104:   *state = 0;
    105: #endif
    106:   PetscFunctionReturn(PETSC_SUCCESS);
    107: }

    109: /*
    110:    SlepcResetFlushToZero - Reset the FTZ flag in floating-point arithmetic.
    111: */
    112: static inline PetscErrorCode SlepcResetFlushToZero(unsigned int *state)
    113: {
    114:   PetscFunctionBegin;
    115: #if defined(PETSC_HAVE_XMMINTRIN_H) && defined(_MM_FLUSH_ZERO_MASK) && defined(__SSE__)
    116:   _MM_SET_FLUSH_ZERO_MODE(*state & _MM_FLUSH_ZERO_MASK);
    117: #else
    118:   *state = 0;
    119: #endif
    120:   PetscFunctionReturn(PETSC_SUCCESS);
    121: }