/*
 * utils.c
 *
 * Utility stuff
 *
 * (c) 2006-2009 Thomas White <thomas.white@desy.de>
 *
 * pattern_sim - Simulate diffraction patterns from small crystals
 *
 */

#include <math.h>
#include <string.h>

#include "utils.h"


/* Return the MOST POSITIVE of two numbers */
unsigned int biggest(signed int a, signed int b)
{
	if ( a>b ) {
		return a;
	}
	return b;
}


/* Return the LEAST POSITIVE of two numbers */
unsigned int smallest(signed int a, signed int b)
{
	if ( a<b ) {
		return a;
	}
	return b;
}


double distance(double x1, double y1, double x2, double y2)
{
	return sqrt((x2-x1)*(x2-x1) + (y2-y1)*(y2-y1));
}


double modulus(double x, double y, double z)
{
	return sqrt(x*x + y*y + z*z);
}


double modulus_squared(double x, double y, double z) {
	return x*x + y*y + z*z;
}


double distance3d(double x1, double y1, double z1,
                  double x2, double y2, double z2)
{
	return modulus(x1-x2, y1-y2, z1-z2);
}


/* Angle between two vectors.  Answer in radians */
double angle_between(double x1, double y1, double z1,
                     double x2, double y2, double z2)
{
	double mod1 = modulus(x1, y1, z1);
	double mod2 = modulus(x2, y2, z2);
	return acos( (x1*x2 + y1*y2 + z1*z2) / (mod1*mod2) );
}


/* As above, answer in degrees */
double angle_between_d(double x1, double y1, double z1,
                       double x2, double y2, double z2)
{
	return rad2deg(angle_between(x1, y1, z1, x2, y2, z2));
}


/* Wavelength of an electron (in m) given accelerating potential (in V) */
double lambda(double V)
{
	double m = 9.110E-31;
	double h = 6.625E-34;
	double e = 1.60E-19;
	double c = 2.998E8;

	return h / sqrt(2*m*e*V*(1+((e*V) / (2*m*c*c))));
}


size_t skipspace(const char *s)
{
	size_t i;

	for ( i=0; i<strlen(s); i++ ) {
		if ( (s[i] != ' ') && (s[i] != '\t') ) return i;
	}

	return strlen(s);
}


void chomp(char *s)
{
	size_t i;

	if ( !s ) return;

	for ( i=0; i<strlen(s); i++ ) {
		if ( (s[i] == '\n') || (s[i] == '\r') ) {
			s[i] = '\0';
			return;
		}
	}
}


int sign(double a)
{
	if ( a < 0 ) return -1;
	if ( a > 0 ) return +1;
	return 0;
}