Date: 2023-09-05T10:17:38+00:00

Actual source code: slepcmath.h
slepc-3.19.2 2023-09-05
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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: /* SUBMANSEC = sys */

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

     33: static inline PetscReal SlepcDefaultTol(PetscReal tol)
     34: {
     35:   return tol == (PetscReal)PETSC_DEFAULT ? SLEPC_DEFAULT_TOL : tol;
     36: }

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

     42:    Not Collective

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

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

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

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

     59:   w = PetscMax(xabs,yabs);
     60:   z = PetscMin(xabs,yabs);
     61:   if (PetscUnlikely(z == 0.0)) return w;
     62:   t = z/w;
     63:   return w*PetscSqrtReal(1.0+t*t);
     64: }

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

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

     73:    Not Collective

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

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

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

     85:    This function is not available from Fortran.

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

     95: #endif

     97: /*
     98:    SlepcSetFlushToZero - Set the FTZ flag in floating-point arithmetic.
     99: */
    100: static inline PetscErrorCode SlepcSetFlushToZero(unsigned int *state)
    101: {
    102:   PetscFunctionBegin;
    103: #if defined(PETSC_HAVE_XMMINTRIN_H) && defined(_MM_FLUSH_ZERO_ON) && defined(__SSE__)
    104:   *state = _MM_GET_FLUSH_ZERO_MODE();
    105:   _MM_SET_FLUSH_ZERO_MODE(_MM_FLUSH_ZERO_ON);
    106: #else
    107:   *state = 0;
    108: #endif
    109:   PetscFunctionReturn(PETSC_SUCCESS);
    110: }

    112: /*
    113:    SlepcResetFlushToZero - Reset the FTZ flag in floating-point arithmetic.
    114: */
    115: static inline PetscErrorCode SlepcResetFlushToZero(unsigned int *state)
    116: {
    117:   PetscFunctionBegin;
    118: #if defined(PETSC_HAVE_XMMINTRIN_H) && defined(_MM_FLUSH_ZERO_MASK) && defined(__SSE__)
    119:   _MM_SET_FLUSH_ZERO_MODE(*state & _MM_FLUSH_ZERO_MASK);
    120: #else
    121:   *state = 0;
    122: #endif
    123:   PetscFunctionReturn(PETSC_SUCCESS);
    124: }