slamchf77.f man page

slamchf77.f —

Synopsis

Functions/Subroutines

REAL function slamch (CMACH)
SLAMCHF77 deprecated
subroutine slamc1 (BETA, T, RND, IEEE1)
SLAMC1
subroutine slamc2 (BETA, T, RND, EPS, EMIN, RMIN, EMAX, RMAX)
SLAMC2
REAL function slamc3 (A, B)
SLAMC3
subroutine slamc4 (EMIN, START, BASE)
SLAMC4
subroutine slamc5 (BETA, P, EMIN, IEEE, EMAX, RMAX)
SLAMC5

Function/Subroutine Documentation

subroutine slamc1 (integerBETA, integerT, logicalRND, logicalIEEE1)

SLAMC1 Purpose:

SLAMC1 determines the machine parameters given by BETA, T, RND, and
IEEE1.

Parameters:

BETA

The base of the machine.

T

The number of ( BETA ) digits in the mantissa.

RND

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

Specifies whether rounding appears to be done in the IEEE
'round to nearest' style.

Author:

LAPACK is a software package provided by Univ. of Tennessee, Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..

Date:

April 2012

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.

Definition at line 210 of file slamchf77.f.

subroutine slamc2 (integerBETA, integerT, logicalRND, realEPS, integerEMIN, realRMIN, integerEMAX, realRMAX)

SLAMC2 Purpose:

SLAMC2 determines the machine parameters specified in its argument
list.

Author:

LAPACK is a software package provided by Univ. of Tennessee, Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..

Date:

April 2012

Parameters:

BETA

The base of the machine.

T

The number of ( BETA ) digits in the mantissa.

RND

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

The smallest positive number such that
   fl( 1.0 - EPS ) .LT. 1.0,
where fl denotes the computed value.

EMIN

The minimum exponent before (gradual) underflow occurs.

RMIN

The smallest normalized number for the machine, given by
BASE**( EMIN - 1 ), where  BASE  is the floating point value
of BETA.

EMAX

The maximum exponent before overflow occurs.

RMAX

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.

Definition at line 423 of file slamchf77.f.

REAL function slamc3 (realA, realB)

SLAMC3 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.

Parameters:

A
B

The values A and B.

Definition at line 646 of file slamchf77.f.

subroutine slamc4 (integerEMIN, realSTART, integerBASE)

SLAMC4 Purpose:

SLAMC4 is a service routine for SLAMC2.

Parameters:

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

The starting point for determining EMIN.

BASE

The base of the machine.

Definition at line 693 of file slamchf77.f.

subroutine slamc5 (integerBETA, integerP, integerEMIN, logicalIEEE, integerEMAX, realRMAX)

SLAMC5 Purpose:

SLAMC5 attempts to compute RMAX, the largest machine floating-point
number, without overflow.  It assumes that EMAX + abs(EMIN) sum
approximately to a power of 2.  It will fail on machines where this
assumption does not hold, for example, the Cyber 205 (EMIN = -28625,
EMAX = 28718).  It will also fail if the value supplied for EMIN is
too large (i.e. too close to zero), probably with overflow.

Parameters:

BETA

The base of floating-point arithmetic.

P

The number of base BETA digits in the mantissa of a
floating-point value.

EMIN

The minimum exponent before (gradual) underflow.

IEEE

A logical flag specifying whether or not the arithmetic
system is thought to comply with the IEEE standard.

EMAX

The largest exponent before overflow

RMAX

The largest machine floating-point number.

Definition at line 801 of file slamchf77.f.

REAL function slamch (characterCMACH)

SLAMCHF77 deprecated Purpose:

SLAMCH determines single precision machine parameters.

Parameters:

CMACH

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)

Author:

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Date:

April 2012

Definition at line 68 of file slamchf77.f.

Author

Generated automatically by Doxygen for LAPACK from the source code.

Referenced By

slamc1(3), slamc2(3), slamc4(3) and slamc5(3) are aliases of slamchf77.f(3).

Sat Nov 16 2013 Version 3.4.2 LAPACK