Date: 2022-03-31T15:29:40+00:00

Actual source code: slepcmath.h
slepc-3.17.0 2022-03-31
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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: #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: #define SlepcDefaultTol(tol) (((tol)==PETSC_DEFAULT)?SLEPC_DEFAULT_TOL:(tol))

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

     37:    Not Collective

     39:    Input parameters:
     40: .  x,y - the real numbers

     42:    Output parameter:
     43: .  return - the result

     45:    Note:
     46:    This function is not available from Fortran.

     48:    Level: developer
     49: @*/
     50: static inline PetscReal SlepcAbs(PetscReal x,PetscReal y)
     51: {
     52:   PetscReal w,z,t,xabs=PetscAbs(x),yabs=PetscAbs(y);

     54:   w = PetscMax(xabs,yabs);
     55:   z = PetscMin(xabs,yabs);
     56:   if (PetscUnlikely(z == 0.0)) return w;
     57:   t = z/w;
     58:   return w*PetscSqrtReal(1.0+t*t);
     59: }

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

     65:    Synopsis:
     66:    PetscReal SlepcAbsEigenvalue(PetscScalar x,PetscScalar y)

     68:    Not Collective

     70:    Input parameters:
     71: +  x  - the real part of the complex number
     72: -  y  - the imaginary part of the complex number

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

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

     80:    This function is not available from Fortran.

     82:    Level: developer
     83: M*/
     84: #if !defined(PETSC_USE_COMPLEX)
     85: #define SlepcAbsEigenvalue(x,y) SlepcAbs(x,y)
     86: #else
     87: #define SlepcAbsEigenvalue(x,y) PetscAbsScalar(x)
     88: #endif

     90: #endif

     92: /*
     93:    SlepcSetFlushToZero - Set the FTZ flag in floating-point arithmetic.
     94: */
     95: static inline PetscErrorCode SlepcSetFlushToZero(unsigned int *state)
     96: {
     97: #if defined(PETSC_HAVE_XMMINTRIN_H) && defined(_MM_FLUSH_ZERO_ON) && defined(__SSE__)
     98:   *state = _MM_GET_FLUSH_ZERO_MODE();
     99:   _MM_SET_FLUSH_ZERO_MODE(_MM_FLUSH_ZERO_ON);
    100: #else
    101:   *state = 0;
    102: #endif
    103:   PetscFunctionReturn(0);
    104: }

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