c_funcs.h

#ifndef __C_FUNCS
#define __C_FUNCS

#include <math.h>

#define max(a,b) (a < b) ? b : a

double c_sum(double *t, int N)
{
	int i;
	double sum=0.0f;
	for(i=0;i<N;i++)
	{
		sum += t[i];
	}

	return sum;
}

double c_norm2(double *t, int N)
{
	int i;
	double norm2=0.0f;
	for(i=0;i<N;i++)
	{
		norm2 += t[i]*t[i];
	}

	return sqrt(norm2);
}

double c_normalize(double *t, int N)
{
	int i;
	double norm2 = c_norm2(t,N);

	for(i=0;i<N;i++)
	{
		t[i] /= norm2;
	}

	return norm2;
}

double c_norm1(double *t, int N)
{
	int i;
	double norm1=0.f;

	for(i=0;i<N;i++)
	{
		norm1 += max(t[i],-t[i]);
	}

	return norm1;
}

void c_proxl1(double *t, int N, double lambda)
{
	int i;

	for(i=0;i<N;i++)
	{
		if(t[i] >= 0)
		{
			t[i] = fmax(0.0, t[i]-lambda);
		} else {
			t[i] = -fmax(0.0, -t[i]-lambda);
		}
	}
}

void c_projLinf(double *t, int N, double min, double max)
{
	int i;

	for(i=0;i<N;i++)
	{
		if(t[i] > max) t[i] = max;
		if(t[i] < min) t[i] = min;
	}
}

void c_projBox(double *t, int N, double r)
{
	c_projLinf(t, N, -r, r);
}

void c_proxl2square(double *t, int N, double lambda)
{
	int i;

	for(i=0; i<N;i++)
	{
		t[i] = t[i] / (1.0 + lambda);
	}
}

int array_equality(double *x, double *y, int N)
{
	int i;
	for(i=0;i<N;i++)
	{
		if(fabs(x[i]-y[i]) > 1e-5)
		{
			return 0;
		}
	}

	return 1;
}

#endif