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/* Copyright (c) 2019, Anthony Latorre <tlatorre at uchicago>
*
* This program is free software: you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the Free
* Software Foundation, either version 3 of the License, or (at your option)
* any later version.
* This program is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
* more details.
* You should have received a copy of the GNU General Public License along with
* this program. If not, see <https://www.gnu.org/licenses/>.
*/
#include "vector.h"
#include <math.h>
void normalize(double *a)
{
double c;
c = 1.0/NORM(a);
MUL(a,c);
}
void rotate(double *dest, double *v, double *n, double phi)
{
/* Rotate the vector `v` through an angle `phi` about the axis `n`. */
double temp[3], cos_theta;
cos_theta = cos(phi);
COPY(dest,v);
MUL(dest,cos_theta);
CROSS(temp,n,v);
MUL(temp,sin(phi));
ADD(dest,dest,temp);
COPY(temp,n);
MUL(temp,DOT(n,v)*(1-cos_theta));
ADD(dest,dest,temp);
}
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