--- name: "slamc5" section: "3" platform: "linux" package: "liblapack-doc-man" version: "3.5.0-4" release: "Debian 8 (Jessie)" platforms: ["linux"] url: "https://new.carta.tech/slamchf77.f" --- # slamc5(3) Part of [slamchf77.f(3)](/slamchf77.f/3.md). ## NAME 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.