Date: 2026-01-20T11:35:07+00:00

Actual source code: slepcmath.h

      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_DETERMINE ? 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:    Fortran 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 == PetscRealConstant(0.0))) return w;
     61:   t = z/w;
     62:   return w*PetscSqrtReal(PetscRealConstant(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, i.e., the result is $|x|$.

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

    110: /*
    111:    SlepcResetFlushToZero - Reset the FTZ flag in floating-point arithmetic.
    112: */
    113: static inline PetscErrorCode SlepcResetFlushToZero(unsigned int *state)
    114: {
    115:   PetscFunctionBegin;
    116: #if defined(PETSC_HAVE_XMMINTRIN_H) && defined(_MM_FLUSH_ZERO_MASK) && defined(__SSE__)
    117:   _MM_SET_FLUSH_ZERO_MODE(*state & _MM_FLUSH_ZERO_MASK);
    118: #else
    119:   *state = 0;
    120: #endif
    121:   PetscFunctionReturn(PETSC_SUCCESS);
    122: }