AROSAmiga Research OS

Previous Next Top of Manual blank.gif

AROS - The Amiga Research OS


Documentation
    AutoDocs
        Exec.library
        MathFFP.library
        MathIEEEDoubleBase
        MathIEEEDoubleTrans
        MathIEEESingleBase
        MathIEEESingleTrans
        MathTrans
            SPCosh
            SPSinh
            SPSin
            SPLog
            SPTieee
            SPExp
            SPAsin
            SPTanh
            SPTan
            SPAcos
            SPFieee
            SPSqrt
            SPAtan
            SPLog10
            SPCos
            SPSincos
            SPPow
NAME
#include <libraries/mathffp.h>
#include <aros/libcall.h>
#include <proto/mathffp.h>
#include <proto/mathtrans.h>
#include <proto/exec.h>
#include <exec/types.h>

float SPLog ()

SYNOPSIS
float fnum1

FUNCTION
Calculate logarithm (base 10) of the given ffp number
INPUTS
fnum1
Motorola fast floating point number

RESULT
ffp-number flags: zero : result is zero negative : result is negative overflow : argument was negative
NOTES
EXAMPLE

BUGS
SEE ALSO
MathTrans

INTERNALS
ALGORITHM: If the Argument is negative set overflow-flag and return 0. If the Argument is 0 return 0xffffffff. All other cases: (ld is the logarithm with base 2) (ln is the logarithm with base e)
fnum1 = M * 2^E

ln fnum1 = ln ( M * 2^E ) =

= ln M + ln 2^E =

= ln M + E * ln (2) =

ld M        ld 2
= ----- + E * ----- =      [ld 2 = 1]
ld e        ld e

ld M + E
= --------
ld e
ld e can be precalculated, of course. For calculating ld M see file intern_spld.c


Previous Next Top of Manual blank.gif
minilogo.gif

Amiga® is a trademark of Amiga Inc. All other trademarks belong to their respective owners.

Copyright © AROS - The Amiga Research OS
All Rights Reserved
Comments to webmaster: digulla@aros.org
Generated: Tue Sep 4, 2001