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slamchf77.f(3) LAPACK slamchf77.f(3)slamchf77.fNAME-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) SLAMC5SYNOPSISFunction/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 =, 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.-28625AuthorGenerated automatically by Doxygen for LAPACK from the source code.Version 3.4.2Tue Sep 25 2012 slamchf77.f(3)

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