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/*
* utils.c
*
* Utility stuff
*
* (c) 2007 Thomas White <taw27@cam.ac.uk>
* Gordon Ball <gfb21@cam.ac.uk>
*
* dtr - Diffraction Tomography Reconstruction
*
*/
#include <math.h>
#include <gsl/gsl_matrix.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);
}
/* Angle between two vectors. Answer in degrees */
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)))/M_PI) * 180;
}
/* 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))));
}
/* Renormalise a gsl_matrix to 0->1
* Re-written to use gsl_matrix native functions */
void matrix_renormalise(gsl_matrix *m) {
double max,min;
gsl_matrix_minmax(m,&min,&max);
gsl_matrix_add_constant(m,0.-min);
gsl_matrix_scale(m,1./(max-min));
}
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