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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 "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;
}
void mapping_rotate(double x, double y, double z,
double *ddx, double *ddy, double *ddz,
double omega, double tilt)
{
double nx, ny, nz;
double x_temp, y_temp, z_temp;
/* First: rotate image clockwise until tilt axis is aligned
* horizontally. */
nx = x*cos(omega) + y*sin(omega);
ny = -x*sin(omega) + y*cos(omega);
nz = z;
/* Now, tilt about the x-axis ANTICLOCKWISE around +x, i.e. the
* "wrong" way. This is because the crystal is rotated in the
* experiment, not the Ewald sphere. */
x_temp = nx; y_temp = ny; z_temp = nz;
nx = x_temp;
ny = cos(tilt)*y_temp + sin(tilt)*z_temp;
nz = -sin(tilt)*y_temp + cos(tilt)*z_temp;
/* Finally, reverse the omega rotation to restore the location of the
* image in 3D space */
x_temp = nx; y_temp = ny; z_temp = nz;
nx = x_temp*cos(-omega) + y_temp*sin(-omega);
ny = -x_temp*sin(-omega) + y_temp*cos(-omega);
nz = z_temp;
*ddx = nx;
*ddy = ny;
*ddz = nz;
}
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