QuEST_precision.h

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// Distributed under MIT licence. See https://github.com/QuEST-Kit/QuEST/blob/master/LICENCE.txt for details
 
# include <math.h>
 
# ifndef QUEST_PRECISION_H
# define QUEST_PRECISION_H
 
 
// set default double precision if not set during compilation
# ifndef QuEST_PREC
# define QuEST_PREC 2
# endif
 
 
/*
 * Single precision, which uses 4 bytes per amplitude component
 */
# if QuEST_PREC==1
    # define qreal float
    // \cond HIDDEN_SYMBOLS   
    # define MPI_QuEST_REAL MPI_FLOAT
    # define MPI_MAX_AMPS_IN_MSG (1LL<<29) // must be 2^int
    # define REAL_STRING_FORMAT "%.8f"
    # define REAL_QASM_FORMAT "%.8g"
    # define REAL_EPS 1e-5
    # define absReal(X) fabs(X) // not fabsf(X) - better to return doubles where possible
    // \endcond
/*
 * Double precision, which uses 8 bytes per amplitude component
 */
# elif QuEST_PREC==2
    # define qreal double
    // \cond HIDDEN_SYMBOLS   
    # define MPI_QuEST_REAL MPI_DOUBLE
    # define MPI_MAX_AMPS_IN_MSG (1LL<<28) // must be 2^int
    # define REAL_STRING_FORMAT "%.14f"
    # define REAL_QASM_FORMAT "%.14g"
    # define REAL_EPS 1e-13
    # define absReal(X) fabs(X)
    // \endcond
/*
 * Quad precision, which uses 16 bytes per amplitude component.
 * This is not compatible with most GPUs.
 */
# elif QuEST_PREC==4
    # define qreal long double
    // \cond HIDDEN_SYMBOLS   
    # define MPI_QuEST_REAL MPI_LONG_DOUBLE
    # define MPI_MAX_AMPS_IN_MSG (1LL<<27) // must be 2^int
    # define REAL_STRING_FORMAT "%.17Lf"
    # define REAL_QASM_FORMAT "%.17Lg"
    # define REAL_EPS 1e-14
    # define absReal(X) fabsl(X)
    // \endcond
# endif
 
 
# endif // QUEST_PRECISION_H