Module bhoelHelper.machar

Declared in module bhoelHelper

def machar()
string __author__ = 'Berthold H\366llmann, bhoel@starship.python.net'
string __file__ = '../bhoelHelper/machar.pyc'
string __version__ = '1.1'
float eps = 2.22044604925e-16
float epsneg = 1.11022302463e-16
int ibeta = 2
int iexp = 11
int irnd = 5
int it = 53
int machdep = -52
int maxexp = 1024
int minexp = -1022
int negep = -53
int ngrd = 0
float xmax = 1.79769313486e+308
float xmin = 2.22507385851e-308

Description

Function to determine machine-specific parameters affecting floating-point arithmetic.

This is build after "NUMERICAL RECIPES in C", second edition, Reprinted 1996, pp. 889.

machar()

Determines and returns machine-specific parameters affecting floating-point arithmetic. Returned values include:

ibeta: The radix in which numbers are represented, almost always 2, but occasionally 16, or even 10
it: The number of base-'ibeta' digits in the floating point mantissa
machep: Is the exponent of the smallest (mos negative) power if ibeta that, added to 1.0 gives something different from 1.0.
eps: Is the floating-point number ibeta'**'machdep, loosly referred to as the 'floating-point precision.'
negep: Is the exponenet of the smalles power of ibeta that, subtracted from 1.0, gives something different from 1.0.
epsneg: Is ibeta'**'negep, another way of defining floating-point precision. Not infrequently epsneg is 0.5 times eps; occasionally eps and epsneg are equal.
iexp: Is the number of bits in the exponent (including its sign or bias)
minexp: Is the smallest (most negative) power if ibeta consistent with there no leading zeros in the mantissa.
xmin: Is the floating-point number ibeta'**'minexp, generally the smallest (in magnitude) usable floating value
maxexp: Is the smallest (positive) power of ibeta that causes overflow.
xmax: Is (1-'epsneg')x'ibeta'**'maxexp', generally the largest (in magnitude) usable floating value.
irnd: Returns a code in the range 0...5, giving information on what kind of rounding is done in addition, and on how underflow is handled.

If irnd returns 2 or 5, then your computer is compilant with the IEEE standard for rounding. If it returns 1 or 4, then it is doing some kind of rounding, but not the IEEE standard. If irnd returns 0 or 3, then it is truncating the result, not rounding it. ngrd -- Is the number of 'guard digits' used when truncating the ploduct of two mantissas to fit the representationThis is taken from "NUMERICAL RECIPES in C", second edition, Reprinted 1996.

Author: Berthold H\366llmann
Version: 1.1