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;include "maplec.h"
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ALGEB ExtractElems( MKernelVector kv, ALGEB args )
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{
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char relation;
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int n, elems, result_elems, count, i;
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ALGEB Matrix, result;
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RTableSettings settings;
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M_INT bounds[2];
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/*
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basic argument checking
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*/
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if( MapleNumArgs(kv,args) != 3
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|| !IsMapleRTable(kv,(ALGEB)args[1])
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|| !IsMapleInteger32(kv,(ALGEB)args[2])
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|| !IsMapleString(kv,(ALGEB)args[3]) )
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{
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MapleRaiseError(kv,"usage: ExtractElems(Matrix,integer,string)");
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}
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/*
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find more about the Matrix
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*/
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Matrix = (ALGEB)args[1];
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RTableGetSettings(kv,&settings,Matrix);
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if( settings.data_type != RTABLE_INTEGER32
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|| settings.storage != RTABLE_RECT
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|| !IsMapleNULL(kv,settings.index_functions) )
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{
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/* not the format we wanted -- make a copy */
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settings.data_type = RTABLE_INTEGER32;
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settings.storage = RTABLE_RECT;
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settings.index_functions = ToMapleNULL(kv);
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settings.foreign = FALSE;
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Matrix = RTableCopy(kv,&settings,Matrix);
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}
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/*
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get a pointer to the actual Matrix data
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*/
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elems = (int)RTableDataBlock(kv,Matrix);
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/*
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translate the other arguments
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*/
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n = MapleToInteger32(kv,(ALGEB)args[2]);
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relation = MapleToString(kv,(ALGEB)args[3]);
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/*
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scan over the elements linearly -- we don't need to look at
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RTableNumDimensions, RTableLowerBound, and RTableUpperBound
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because we don't care where the elements are, just what they are.
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*/
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/*
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first count the elements that satisfy the relation
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*/
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count = 0;
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switch( relation[0] ) {
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case '>':
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for( i=0; i<RTableNumElements(kv,Matrix); ++i )
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if( elems[i] > n ) count++;
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break;
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case '<':
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for( i=0; i<RTableNumElements(kv,Matrix); ++i )
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if( elems[i] < n ) count++;
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break;
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case '=':
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for( i=0; i<RTableNumElements(kv,Matrix); ++i )
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if( elems[i] == n ) count++;
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break;
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case '!':
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for( i=0; i<RTableNumElements(kv,Matrix); ++i )
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if( elems[i] != n ) count++;
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break;
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default:
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MapleRaiseError1(kv,"invalid relation %1",(ALGEB)args[3]);
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}
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/*
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create a new Array to store the result
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*/
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RTableGetDefaults(kv,&settings);
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settings.data_type = RTABLE_INTEGER32;
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settings.subtype = RTABLE_ARRAY;
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settings.num_dimensions = 1;
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bounds[0] = 1;
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bounds[1] = count;
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result = RTableCreate(kv,&settings,NULL,bounds);
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/*
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fill in the result
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*/
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result_elems = (int)RTableDataBlock(kv,result);
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count = 0;
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switch( relation[0] ) {
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case '>':
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for( i=0; i<RTableNumElements(kv,Matrix); ++i )
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if( elems[i] > n ) result_elems[count++] = elems[i];
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break;
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case '<':
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for( i=0; i<RTableNumElements(kv,Matrix); ++i )
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if( elems[i] < n ) result_elems[count++] = elems[i];
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break;
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case '=':
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for( i=0; i<RTableNumElements(kv,Matrix); ++i )
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if( elems[i] == n ) result_elems[count++] = elems[i];
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break;
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case '!':
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for( i=0; i<RTableNumElements(kv,Matrix); ++i )
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if( elems[i] != n ) result_elems[count++] = elems[i];
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break;
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}
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/*
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display a message
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*/
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InitMaplePrintf(kv);
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MaplePrintf("%d element%s satisfied the relation elem[i] %s %d.\n\n",
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count, count==1 ? "" : "s",relation,n);
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/*
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return the Array we created
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*/
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return( result );
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}
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