MapleEvalhf - evaluate an object using hardware floats in external code
EvalhfMapleProc - evaluate a procedure using hardware floats in external code
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Calling Sequence
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MapleEvalhf(kv, s)
EvalhfMapleProc(kv, fn, n, args)
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Parameters
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kv
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-
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kernel handle of type MKernelVector
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s
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-
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type ALGEB object
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fn
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-
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Maple FUNCTION object
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n
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-
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number of arguments
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args
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-
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array of n hardware floats
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Description
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•
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MapleEvalhf evaluates an expression to a numerical value using the hardware floating-point of the underlying system. This command is equivalent to the Maple function, evalhf.
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EvalhfMapleProc evaluates the function, f(args), to a numerical value using evalhf. The n arguments provided are all 64-bit hardware floating-point numbers. The first argument must be inserted at args[1]. For example, to call f(3.14,2.718), set args[1] = 3.14, and args[2] = 2.718. The value at args[0] is not used.
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Examples
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#include <math.h>
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#include "maplec.h"
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ALGEB M_DECL MyNewton( MKernelVector kv, ALGEB *args )
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{
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M_INT i;
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FLOAT64 guess[2], tolerance;
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ALGEB f, fprime, x;
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if( 3 != MapleNumArgs(kv,(ALGEB)args) ) {
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MapleRaiseError(kv,"three arguments expected");
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return( NULL );
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}
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if( IsMapleProcedure(kv,args[1]) ) {
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f = args[1];
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}
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else {
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ALGEB indets;
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indets = EvalMapleProc(kv,ToMapleName(kv,"indets",TRUE),1,args[1]);
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if( !IsMapleSet(kv,indets) || MapleNumArgs(kv,indets) != 1 ) {
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MapleRaiseError(kv,"unable to find roots");
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return( NULL );
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}
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i = 1;
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f = EvalMapleProc(kv,ToMapleName(kv,"unapply",TRUE),2,args[1],
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MapleSelectIndexed(kv,indets,1,&i));
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if( !f || !IsMapleProcedure(kv,f) ) {
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MapleRaiseError(kv,"unable to convert first arg to a procedure");
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return( NULL );
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}
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}
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x = ToMapleName(kv,"x",FALSE);
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fprime = EvalMapleProc(kv,ToMapleName(kv,"unapply",TRUE),2,
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EvalMapleProc(kv,ToMapleName(kv,"diff",TRUE),2,
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ToMapleFunction(kv,f,1,x),x),x);
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if( !fprime || !IsMapleProcedure(kv,fprime) ) {
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MapleRaiseError(kv,"unable to compute derivative");
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return( NULL );
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}
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guess[1] = MapleEvalhf(kv,args[2]);
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tolerance = MapleEvalhf(kv,args[3]);
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for( i=0; i<500; ++i ) {
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if( fabs(EvalhfMapleProc(kv,f,1,guess)) <= tolerance )
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break;
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guess[1] = guess[1] - EvalhfMapleProc(kv,f,1,guess) /
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EvalhfMapleProc(kv,fprime,1,guess);
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}
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if( i == 500 ) {
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MapleRaiseError(kv,"unable to find root after 500 iterations");
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return( NULL );
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}
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return( ToMapleFloat(kv,guess[1]) );
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}
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Execute the external function from Maple.
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