#include <stdio.h>
#include "Cnames.h"
Defines | |
#define | TRUE_ (1) |
#define | FALSE_ (0) |
#define | min(a, b) ((a) <= (b) ? (a) : (b)) |
#define | max(a, b) ((a) >= (b) ? (a) : (b)) |
#define | abs(x) ((x) >= 0 ? (x) : -(x)) |
#define | dabs(x) (double)abs(x) |
Functions | |
float | slamch_ (char *cmach) |
int | slamc1_ (int *beta, int *t, int *rnd, int *ieee1) |
int | slamc2_ (int *beta, int *t, int *rnd, float *eps, int *emin, float *rmin, int *emax, float *rmax) |
double | slamc3_ (float *a, float *b) |
int | slamc4_ (int *emin, float *start, int *base) |
-- LAPACK auxiliary routine (version 2.0) -- Univ. of Tennessee, Univ. of California Berkeley, NAG Ltd., Courant Institute, Argonne National Lab, and Rice University October 31, 1992
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Purpose =======
SLAMC1 determines the machine parameters given by BETA, T, RND, and IEEE1.
Arguments =========
BETA (output) INT The base of the machine.
T (output) INT The number of ( BETA ) digits in the mantissa.
RND (output) INT Specifies whether proper rounding ( RND = .TRUE. ) or chopping ( RND = .FALSE. ) occurs in addition. This may not
be a reliable guide to the way in which the machine performs
its arithmetic.
IEEE1 (output) INT Specifies whether rounding appears to be done in the IEEE 'round to nearest' style.
Further Details ===============
The routine is based on the routine ENVRON by Malcolm and incorporates suggestions by Gentleman and Marovich. See
Malcolm M. A. (1972) Algorithms to reveal properties of floating-point arithmetic. Comms. of the ACM, 15, 949-951.
Gentleman W. M. and Marovich S. B. (1974) More on algorithms that reveal properties of floating point arithmetic units. Comms. of the ACM, 17, 276-277.
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Purpose =======
SLAMC2 determines the machine parameters specified in its argument list.
Arguments =========
BETA (output) INT The base of the machine.
T (output) INT The number of ( BETA ) digits in the mantissa.
RND (output) INT Specifies whether proper rounding ( RND = .TRUE. ) or chopping ( RND = .FALSE. ) occurs in addition. This may not
be a reliable guide to the way in which the machine performs
its arithmetic.
EPS (output) FLOAT The smallest positive number such that
fl( 1.0 - EPS ) .LT. 1.0,
where fl denotes the computed value.
EMIN (output) INT The minimum exponent before (gradual) underflow occurs.
RMIN (output) FLOAT The smallest normalized number for the machine, given by BASE**( EMIN - 1 ), where BASE is the floating point value
of BETA.
EMAX (output) INT The maximum exponent before overflow occurs.
RMAX (output) FLOAT The largest positive number for the machine, given by BASE**EMAX * ( 1 - EPS ), where BASE is the floating point
value of BETA.
Further Details ===============
The computation of EPS is based on a routine PARANOIA by W. Kahan of the University of California at Berkeley.
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Purpose =======
SLAMC3 is intended to force A and B to be stored prior to doing
the addition of A and B , for use in situations where optimizers
might hold one of these in a register.
Arguments =========
A, B (input) FLOAT The values A and B.
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Purpose =======
SLAMC4 is a service routine for SLAMC2.
Arguments =========
EMIN (output) EMIN The minimum exponent before (gradual) underflow, computed by
setting A = START and dividing by BASE until the previous A can not be recovered.
START (input) FLOAT The starting point for determining EMIN.
BASE (input) INT The base of the machine.
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Purpose =======
SLAMCH determines single precision machine parameters.
Arguments =========
CMACH (input) CHARACTER*1 Specifies the value to be returned by SLAMCH: = 'E' or 'e', SLAMCH := eps = 'S' or 's , SLAMCH := sfmin = 'B' or 'b', SLAMCH := base = 'P' or 'p', SLAMCH := eps*base = 'N' or 'n', SLAMCH := t = 'R' or 'r', SLAMCH := rnd = 'M' or 'm', SLAMCH := emin = 'U' or 'u', SLAMCH := rmin = 'L' or 'l', SLAMCH := emax = 'O' or 'o', SLAMCH := rmax
where
eps = relative machine precision sfmin = safe minimum, such that 1/sfmin does not overflow base = base of the machine prec = eps*base t = number of (base) digits in the mantissa rnd = 1.0 when rounding occurs in addition, 0.0 otherwise emin = minimum exponent before (gradual) underflow rmin = underflow threshold - base**(emin-1) emax = largest exponent before overflow rmax = overflow threshold - (base**emax)*(1-eps)
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