93 lines
1.5 KiB
C
93 lines
1.5 KiB
C
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/* DEC *Median(pDst,pSrc,n)
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*
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* ARGUMENT
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* DEC *pDst;
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* DEC **pSrc;
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* int n;
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*
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* DESCRIPTION
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* Sets pDst to the median of the n DEC elements of the array pSrc.
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* n <= 0 is not allowed. pDst is unchanged if an error occurs.
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*
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* SIDE EFFECTS
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* None.
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*
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* RETURNS
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* Returns pointer to the average if successful, otherwise
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* returns GM_NULL.
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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_ARGVAL
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* GM_NOMEMORY
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*
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* AUTHOR
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* Jared Levy
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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 <malloc.h>
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#include "gm.h"
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#include "gmsystem.h"
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#ifndef DOS
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extern char *calloc(unsigned ,unsigned );
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#endif
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DEC *Median(pDst,pSrc,n)
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DEC *pDst;
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DEC **pSrc;
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int n;
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{
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int i;
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DEC **tmpa, dsum, *sum=&dsum;
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extern void qsort(char *, unsigned, unsigned, int (*)());
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_MacStart(GM_MEDIAN);
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if (!pSrc) {
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_MacErr(GM_NULLPOINTER);
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_MacRet(GM_NULL);
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}
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if (n<=0) {
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_MacErr(GM_ARGVAL);
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_MacRet(GM_NULL);
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}
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for (i=0; i<n; i++)
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_MacInVarD(pSrc[i]);
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_MacOutVarD(pDst);
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/* allocate array of pointers */
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tmpa = (DEC **) calloc(n, sizeof(DEC *));
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if (!tmpa) {
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_MacErr(GM_NOMEMORY);
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_MacRet(GM_NULL);
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}
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/* copy pointers */
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for (i=0;i<n;i++)
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tmpa[i] = pSrc[i];
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/* sort pointers */
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qsort((void *)tmpa,n,sizeof(DEC *), _SortInc);
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if (n%2)
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_MacDCopy(pDst, tmpa[(n-1)/2]);
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else {
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(void) _AddDec80Bit(sum, tmpa[n/2-1], tmpa[n/2]);
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MultiplyDecimal(pDst, sum, &decPoint5);
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}
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free ((char *) tmpa);
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_MacRet(pDst);
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}
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