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/*
* 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 <stdio.h>
#include "utils.h"
/* 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) );
}
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;
}
}
}
void progress_bar(int val, int total, const char *text)
{
double frac;
int n, i;
char s[1024];
const int width = 50;
frac = (double)val/total;
n = (int)(frac*width);
for ( i=0; i<n; i++ ) s[i] = '=';
for ( i=n; i<width; i++ ) s[i] = '.';
s[width] = '\0';
STATUS("\r%s: |%s|", text, s);
if ( val == total ) STATUS("\n");
fflush(stdout);
}
static int fake_poisson_noise(double expected)
{
double x1, x2, w;
double noise, rf;
do {
x1 = 2.0 * ((double)random()/RAND_MAX) - 1.0;
x2 = 2.0 * ((double)random()/RAND_MAX) - 1.0;
w = pow(x1, 2.0) + pow(x2, 2.0);
} while ( w >= 1.0 );
w = sqrt((-2.0*log(w))/w);
noise = w * x1;
rf = expected + noise*sqrt(expected);
return (int)rf;
}
int poisson_noise(double expected)
{
double L;
int k = 0;
double p = 1.0;
L = exp(-expected);
/* For large values of the mean, we get big problems with arithmetic.
* In such cases, fall back on a Gaussian with the right variance. */
if ( !isnormal(L) ) return fake_poisson_noise(expected);
do {
double r;
k++;
r = (double)random()/(double)RAND_MAX;
p *= r;
} while ( p > L );
return k - 1;
}
double quaternion_modulus(struct quaternion q)
{
return sqrt(q.w*q.w + q.x*q.x + q.y*q.y + q.z*q.z);
}
struct quaternion normalise_quaternion(struct quaternion q)
{
double mod;
struct quaternion r;
mod = quaternion_modulus(q);
r.w = q.w / mod;
r.x = q.x / mod;
r.y = q.y / mod;
r.z = q.z / mod;
return r;
}
struct quaternion random_quaternion()
{
struct quaternion q;
q.w = 2.0*(double)random()/RAND_MAX - 1.0;
q.x = 2.0*(double)random()/RAND_MAX - 1.0;
q.y = 2.0*(double)random()/RAND_MAX - 1.0;
q.z = 2.0*(double)random()/RAND_MAX - 1.0;
q = normalise_quaternion(q);
return q;
}
int quaternion_valid(struct quaternion q)
{
double qmod;
qmod = quaternion_modulus(q);
/* Modulus = 1 to within some tolerance?
* Nasty allowance for floating-point accuracy follows... */
if ( (qmod > 0.999) && (qmod < 1.001) ) return 1;
return 0;
}
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