 	printf("Finished.  nsamps=%d\n", nsamps_tot);
 	printf("Computing Sample mean...\n");
 	compute_sample_mean<<<N, 1>>>(samples, sample_mean, nsamps_tot, N);
-	compute_sample_covariance<<<N, N>>>(samples, sample_covariance, nsamps_tot, N);
+	compute_sample_covariance<<<N*(N+1)/2, 1>>>(samples, sample_covariance, nsamps_tot, N);
 	/*copy back sample  mean*/
 	cudaMemcpy(sample_mean_res, sample_mean, mean_size, cudaMemcpyDeviceToHost);
 	cudaMemcpy(samples_res, samples, samples_size, cudaMemcpyDeviceToHost);

__global__ void compute_sample_covariance(float* samples, float* sample_covariance, int nsamps, int N)
{
	int i = blockIdx.x;
	int j = threadIdx.x;
	sample_covariance[i*N + j] = 0.0;
	for(int samp = 0; samp<nsamps; samp++)
	{
		sample_covariance[i*N+j] += samples[samp*N+i]*samples[samp*N+j];
	}
	sample_covariance[i*N+j] = sample_covariance[i*N+j]/nsamps;

}


	/* Compute sizes of various data structures */
	size_t mean_size = N*sizeof(float);
	size_t cov_size = (N*(N+1)/2)*sizeof(float);
	size_t full_cov_size = N*N*sizof(float);
	size_t samples_size = N*nsamps_tot*sizeof(float);
	
	/* allocate result memory */
