ba237a9d91
Files correlati : Ricompilazione Demo : [ ] Commento : Aggiunti i sorgenti per Greenleaf Math Library (gfm.dll) git-svn-id: svn://10.65.10.50/trunk@10079 c028cbd2-c16b-5b4b-a496-9718f37d4682
99 lines
1.9 KiB
C
Executable File
99 lines
1.9 KiB
C
Executable File
/* DEC *AntiLog10Decimal(pDst,pSrc)
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*
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* ARGUMENT
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* pDst is a DEC pointer to the destination.
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* pSrc is a DEC pointer to the source.
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*
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* DESCRIPTION
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* Takes the base 10 anti-logarithm (power) of pSrc,
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* ie. 10**x, storing result in pDst.
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*
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* RETURNS
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* pDst if successful, GM_NULL otherwise.
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*
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* ALGORITHM
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* Set e**x = 10 ** y, then x*ln(e) = y*ln10. Then, ln(e)=1 by
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* definition, so x = y*ln(10), or y times a constant. Therefore, we
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* set z=y*ln(10), and 10**y = e**z.
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*
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*
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* POSSIBLE ERROR CODES
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*
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* GM_NULLPOINTER
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* GM_OVERFLOW
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* GM_UNDERFLOW
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*
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* AUTHOR
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* Andy Anderson 8-18-87 13:51
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* Copyright (C) 1987-1990 Greenleaf Software Inc. All rights reserved.
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*
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* MODIFICATIONS
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*
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*/
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#include <stdio.h>
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#include "gm.h"
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#include "gmsystem.h"
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DEC *AntiLog10Decimal(pDst,pSrc)
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DEC *pDst;
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DEC *pSrc;
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{
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int i;
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DEC dtemp, *temp=&dtemp, *pt, t1;
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_MacStart(GM_DALOG);
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_MacInVar(pSrc,GM_NULL);
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_MacOutVar(pDst,GM_NULL);
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/* 10**0 is a one by definition */
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if(_MacIsDecZ(pSrc)) {
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pt=&decOne;
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_MacDCopy(pDst,pt);
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_MacRet(pDst);
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}
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pt=&t1;
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_MacDZero(pt);
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/* if the power is integer and small enough, use int power rtn */
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if((IsDecimalInt(pSrc)) && ((pSrc->dc.msd == 0) &&
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(pSrc->ls.lsl[1] == 0L) && (pSrc->dc.sl[1] == 0))
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&& (!(pSrc->dc.sl[0] & 0x8000))) {
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pt->dc.id = 0;
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pt->dc.sl[0] = 10;
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i = _IntPwrDec80Bit(pt,pt,ConvDecimalToInt(pSrc));
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if(i != GM_SUCCESS) {
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_MacErr(i);
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_MacRet(GM_NULL);
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}
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}
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else {
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/* first create z = y*ln10, overflow impossible */
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(void) _MulDec80Bit(temp,pSrc,&decLn10);
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/* then e**(yln10) = 10**y */
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i = _ExpDec80Bit(pt, temp);
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if(i==GM_OVERFLOW) {
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_MacErr(i);
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_MacRet(GM_NULL);
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}
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}
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i = _Sq5UnsTo4Uns(pt); /* reduce to 18-digit */
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if(i!=GM_SUCCESS) {
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_MacErr(GM_OVERFLOW);
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_MacRet(GM_NULL);
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}
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if (_MacIsDecZ(pt)) {
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_MacErr(GM_UNDERFLOW);
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}
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_MacDCopy(pDst,pt);
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_MacRet(pDst);
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}
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