table of contents
/home/abuild/rpmbuild/BUILD/lapack-3.12.0/INSTALL/slamchf77.f(3) | Library Functions Manual | /home/abuild/rpmbuild/BUILD/lapack-3.12.0/INSTALL/slamchf77.f(3) |
NAME¶
/home/abuild/rpmbuild/BUILD/lapack-3.12.0/INSTALL/slamchf77.f
SYNOPSIS¶
Functions/Subroutines¶
real function SLAMCH (cmach)
SLAMCH 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 (integer beta, integer t, logical rnd, logical ieee1)¶
SLAMC1 Purpose:
!> SLAMC1 determines the machine parameters given by BETA, T, RND, and !> IEEE1. !>
Parameters
!> 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
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 206 of file slamchf77.f.
subroutine SLAMC2 (integer beta, integer t, logical rnd, real eps, integer emin, real rmin, integer emax, real rmax)¶
SLAMC2 Purpose:
!> SLAMC2 determines the machine parameters specified in its argument !> list. !>
Author
Parameters
!> 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 418 of file slamchf77.f.
real function SLAMC3 (real a, real b)¶
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. !>
Author
Parameters
!>
B
!> The values A and B. !>
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
B
!> The values A and B. !>
Definition at line 170 of file slamch.f.
subroutine SLAMC4 (integer emin, real start, integer base)¶
SLAMC4 Purpose:
!> SLAMC4 is a service routine for SLAMC2. !>
Parameters
!> 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 688 of file slamchf77.f.
subroutine SLAMC5 (integer beta, integer p, integer emin, logical ieee, integer emax, real rmax)¶
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
!> 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 796 of file slamchf77.f.
real function SLAMCH (character cmach)¶
SLAMCH SLAMCHF77 deprecated
Purpose:
!> !> SLAMCH determines single precision machine parameters. !>
Parameters
!> CMACH is 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) !>
Author
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Purpose:
!> !> SLAMCH determines single precision machine parameters. !>
Parameters
!> 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 California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Definition at line 67 of file slamch.f.
Author¶
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