//
// This file is part of the Bones source-to-source compiler examples. The C-code
// is largely identical in terms of functionality and variable naming to the code
// found in PolyBench/C version 3.2. For more information on PolyBench/C or Bones
// please use the contact information below.
//
// == More information on PolyBench/C
// Contact............Louis-Noel Pouchet <pouchet@cse.ohio-state.edu>
// Web address........http://polybench.sourceforge.net/
// 
// == More information on Bones
// Contact............Cedric Nugteren <c.nugteren@tue.nl>
// Web address........http://parse.ele.tue.nl/bones/
//
// == File information
// Filename...........benchmark/correlation.c
// Author.............Cedric Nugteren
// Last modified on...07-Feb-2013
//

#include "common.h"

// This is 'correlation', a correlation computation algorithm
int main(void) {
	int i,j,j1,j2;
	float meanj;
	
	// Declare arrays on the stack
	float data[N][M];
	float mean[M];
	float stddev[M];
	float symmat[M][M];
	
	// Set the constants
	float float_n = 1.2;
	float eps = 0.1;
	
	// Set the input data
	for (i=0; i<N; i++) {
		for (j=0; j<M; j++) {
			data[i][j] = ((float) i*j) / M;
		}
	}
	
	// Perform the computation
	#pragma scop
	{
		#pragma species kernel data[0:N-1,0:M-1]|chunk(0:N-1,0:0) -> mean[0:M-1]|element
		for (j = 0; j < M; j++) {
			mean[j] = 0.0;
			for (i = 0; i < N; i++) {
				mean[j] += data[i][j];
			}
			mean[j] /= float_n;
		}
		#pragma species endkernel correlation_k1
		#pragma species kernel mean[0:M-1]|element ^ data[0:N-1,0:M-1]|chunk(0:N-1,0:0) -> stddev[0:M-1]|element
		for (j = 0; j < M; j++) {
			stddev[j] = 0.0;
			meanj = mean[j];
			for (i = 0; i < N; i++) {
				stddev[j] += (data[i][j] - meanj) * (data[i][j] - meanj);
			}
			stddev[j] /= float_n;
			stddev[j] = sqrt(stddev[j]);
			stddev[j] = stddev[j] <= eps ? 1.0 : stddev[j];
		}
		#pragma species endkernel correlation_k2
		#pragma species kernel data[0:N-1,0:M-1]|element ^ mean[0:M-1]|element ^ stddev[0:M-1]|element -> data[0:N-1,0:M-1]|element
		for (i = 0; i < N; i++) {
			for (j = 0; j < M; j++) {
				data[i][j] -= mean[j];
				data[i][j] /= sqrt(float_n) * stddev[j];
			}
		}
		#pragma species endkernel correlation_k3
	}
	#pragma endscop
	
	// Calculate the MxM correlation matrix
	for (j1=0; j1<M-1; j1++) {
		symmat[j1][j1] = 1.0;
		for (j2=j1+1; j2<M; j2++) {
			symmat[j1][j2] = 0.0;
			for (i = 0; i<N; i++) {
				symmat[j1][j2] += (data[i][j1] * data[i][j2]);
			}
			symmat[j2][j1] = symmat[j1][j2];
		}
	}
	symmat[M-1][M-1] = 1.0;
	
	// Clean-up and exit the function
	fflush(stdout);
	return 0;
}