/* emacs edit mode for this file is -*- C++ -*- */
/* $Id$ */

ftestSetNameOfGame( gcd.ntl, `"
Usage: gcd.ntl [<options>] [<envSpec>] <f> <g> [<realResult>]
  calculates greatest common divisor of canonical forms <f> and
  <g>.  If the gcd of <f> and <g> is already known, the optional
  canonical form <realResult> may be used to check the result of
  the gcd computation.
  The gcd is calculated using the NTL library.  Thus, <f> and <g>
  have to be univariate polynomials over some finite field or
  over the integers.
"'`' )

//{{{ docu
//
// ftestAlgorithm.m4 - ftestAlgorithm test program.
//
// To create ftestAlgorithm.cc, run m4 using the ftest_util.m4 library in
// the following way:
//
// m4 ftest_util.m4 ftestAlgorithm.m4 > ftestAlgorithm.cc
//
//}}}

#include "ntl_util.h"
ftestPreprocInit();

ftestGlobalInit();

//
// - functions.
//

//{{{ static CanonicalForm normalizeGcd ( const CanonicalForm & f )
//{{{ docu
//
// normalizeGcd() - normalize result of gcd computation for
//   testing.
//
// Unit normalization is done in case of a field, sign
// normalization otherwise.
//
//}}}
static CanonicalForm
normalizeGcd ( const CanonicalForm & f )
{
    if ( getCharacteristic() > 0 || isOn( SW_RATIONAL ) )
	return f/Lc( f );
    else
	return abs( f );
}
//}}}

//{{{ ftestStatusT gcdCheck ( const CanonicalForm & f, const CanonicalForm & g, const CanonicalForm & result, const CanonicalForm & realResult )
//{{{ docu
//
// gcdCheck() - check result of gcd().
//
//}}}
ftestStatusT
gcdCheck ( const CanonicalForm & f, const CanonicalForm & g, const CanonicalForm & result, const CanonicalForm & realResult )
{
    // if realResult is given, use it to compare with result
    if ( ! realResult.isZero() )
	if ( normalizeGcd( realResult ) == normalizeGcd( result ) )
	    return Passed;
	else {
	    ftestError( CheckError, "result and real result differ\n" );
	    return Failed;
	}

    if ( result.isZero() )
	if ( f.isZero() && g.isZero() )
	    return Passed;
	else {
	    ftestError( CheckError, "result is zero but f and g are not\n" );
	    return Failed;
	}

    // compare with Factory's gcd
    CanonicalForm factoryResult = gcd( f, g );
    if ( normalizeGcd( factoryResult ) == normalizeGcd( result ) )
	return Passed;
    else {
	ftestError( CheckError, "result and Factory's result differ\n" );
	return Failed;
    }

    if ( ! divides( result, f ) || ! divides( result, g ) ) {
	ftestError( CheckError, "result is not a common divisor\n" );
	return Failed;
    } else if ( ! gcd( f/result, g/result ).isOne() ) {
	ftestError( CheckError, "result is not greatest common divisor\n" );
	return Failed;
    } else
	return Passed;
}
//}}}

//
// - main program.
//
int
main ( int argc, char ** argv )
{
    // initialization
    ftestMainInit();

    // declare input and output variables
    ftestOutVar( CanonicalForm, result );
    ftestInVar( CanonicalForm, f );
    ftestInVar( CanonicalForm, g );
    ftestInVar( CanonicalForm, realResult );

    // process argument list and set environment
    ftestGetOpts();
    ftestGetEnv();
    ftestGetInVar( f );
    ftestGetInVar( g );
    ftestGetInVar( realResult, 0 );

    // prepare NTL
    setCharacteristicNTL( getCharacteristic() );

    // run gcd from NTL
    if ( getCharacteristic() > 0 ) {
	zz_pX fNTL;
	zz_pX gNTL;
	zz_pX resultNTL;
	fNTL << f;
	gNTL << g;

	// do the test!
	ftestRun( GCD( resultNTL, fNTL, gNTL ); );

	result << resultNTL;
    } else {
	ZZX fNTL;
	ZZX gNTL;
	ZZX resultNTL;
	fNTL << f;
	gNTL << g;

	// do the test!
	ftestRun( GCD( resultNTL, fNTL, gNTL ); );

	result << resultNTL;
    }

    // do the check
    ftestCheck( gcdCheck( f, g, result, realResult ) );

    // print results
    ftestOutput( "gcd(f, g)", result );

    // clean up
    ftestMainExit();
}