/*

* Portions Copyright (c) 2009 Nokia Corporation and/or its subsidiary(-ies).

* All rights reserved.

* This component and the accompanying materials are made available

* under the terms of "Eclipse Public License v1.0"

* which accompanies this distribution, and is available

* at the URL "http://www.eclipse.org/legal/epl-v10.html".

*

* Initial Contributors:

* Nokia Corporation - initial contribution.

*

* Contributors:

*

* Description: 

* The original NIST Statistical Test Suite code is placed in public domain.

* (http://csrc.nist.gov/groups/ST/toolkit/rng/documentation_software.html) 

* 

* This software was developed at the National Institute of Standards and Technology by 

* employees of the Federal Government in the course of their official duties. Pursuant

* to title 17 Section 105 of the United States Code this software is not subject to 

* copyright protection and is in the public domain. The NIST Statistical Test Suite is

* an experimental system. NIST assumes no responsibility whatsoever for its use by other 

* parties, and makes no guarantees, expressed or implied, about its quality, reliability, 

* or any other characteristic. We would appreciate acknowledgment if the software is used.

*/

#include "openc.h"

#include "../include/externs.h"

#include "../include/utilities.h"

#include "../include/cephes.h"

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *

         D I S C R E T E  F O U R I E R  T R A N S F O R M  T E S T 

 * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */

void  __ogg_fdrffti(int n, double* wsave, int* ifac);

void  __ogg_fdrfftf(int n, double* X, double* wsave, int* ifac);

void

DiscreteFourierTransform(int n)

{

	double     p_value, upperBound, percentile, N_l, N_o, d;

	double*    m = NULL;

	double*    X = NULL;

	double*    wsave = NULL;

	int*       ifac = NULL;

	int		i, count;

	if ( ((X = (double*) calloc(n,sizeof(double))) == NULL) ||

		 ((wsave = (double *)calloc(2*n+15,sizeof(double))) == NULL) ||

		 ((ifac = (int *)calloc(15,sizeof(int))) == NULL) ||

		 ((m = (double*)calloc(n/2+1, sizeof(double))) == NULL) ) {

			fprintf(stats[7],"\t\tUnable to allocate working arrays for the DFT.\n");

			if( X != NULL )

				free(X);

			if( wsave != NULL )

				free(wsave);

			if( ifac != NULL )

				free(ifac);

			if( m != NULL )

				free(m);

			return;

	}

	for ( i=0; i<n; i++ )

		X[i] = 2*(int)epsilon[i] - 1;

	__ogg_fdrffti(n, wsave, ifac);		/* INITIALIZE WORK ARRAYS */

	__ogg_fdrfftf(n, X, wsave, ifac);	/* APPLY FORWARD FFT */

	m[0] = sqrt(X[0]*X[0]);	    /* COMPUTE MAGNITUDE */

	for ( i=0; i<n/2; i++ ) {	   	    /* DISPLAY FOURIER POINTS */

		m[i+1] = sqrt(pow(X[2*i+1],2)+pow(X[2*i+2],2)); 

	}

	count = 0;				       /* CONFIDENCE INTERVAL */

	upperBound = sqrt(2.995732274*n);

	for ( i=0; i<n/2; i++ )

		if ( m[i] < upperBound )

			count++;

	percentile = (double)count/(n/2)*100;

	N_l = (double) count;       /* number of peaks less than h = sqrt(3*n) */

	N_o = (double) 0.95*n/2.0;

	d = (N_l - N_o)/sqrt(n/2.0*0.95*0.05);

	p_value = erfc(fabs(d)/sqrt(2.0));

	fprintf(stats[TEST_FFT], "\t\t\t\tFFT TEST\n");

	fprintf(stats[TEST_FFT], "\t\t-------------------------------------------\n");

	fprintf(stats[TEST_FFT], "\t\tCOMPUTATIONAL INFORMATION:\n");

	fprintf(stats[TEST_FFT], "\t\t-------------------------------------------\n");

	fprintf(stats[TEST_FFT], "\t\t(a) Percentile = %f\n", percentile);

	fprintf(stats[TEST_FFT], "\t\t(b) N_l        = %f\n", N_l);

	fprintf(stats[TEST_FFT], "\t\t(c) N_o        = %f\n", N_o);

	fprintf(stats[TEST_FFT], "\t\t(d) d          = %f\n", d);

	fprintf(stats[TEST_FFT], "\t\t-------------------------------------------\n");

	fprintf(stats[TEST_FFT], "%s\t\tp_value = %f\n\n", p_value < ALPHA ? "FAILURE" : "SUCCESS", p_value);

	fprintf(results[TEST_FFT], "%f\n", p_value);

	free(X);

	free(wsave);

	free(ifac);

	free(m);

}