#include <stdio.h>
#include <ctype.h>
#include <math.h>
#include <stdarg.h>

void crossp(float out[],float v[],float w[])
{
        out[0] = v[1] * w[2] - v[2] * w[1];
        out[1] = v[2] * w[0] - v[0] * w[2];
        out[2] = v[0] * w[1] - v[1] * w[0];
        return;
}

float power(float base,int power)
{
        float p;
        for(p=1;power>0;--power)
        {
                p=p*base;
        }
        return p;
}

float prikp(float a[],float b[])
{
        float x;
        x = a[1] * b[1] + a[2] * b[2] + a[0] * b[0];
        return x;
}

void crosspi(int v[],int a[],int b[])
{
        v[0] = a[1] * b[2] - a[2] * b[1];
        v[1] = a[2] * b[0] - a[0] * b[2];
        v[2] = a[0] * b[1] - a[1] * b[0];
        return;
}


float length(float a[])
{
   /* Calculates length of vector a */
   float vectorlength;
   vectorlength = sqrt(power(a[0],2) + power(a[1],2) + power(a[2],2));
   return vectorlength;
}

float lengthi(int a[])
{
   /* Calculates length of vector a */
   float vectorlength;
   vectorlength = sqrt(power(a[0],2) + power(a[1],2) + power(a[2],2));
   return vectorlength;
}

float vektorvinkel(float a[],float b[])
{
        /* CALCULATION OF ANGLE BETWEEN 2 VECTORS; a AND b */
        float x,pi,angle,c,d;
        pi =3.141592;
        angle = 0;
        x = prikp(a,b);
        d = length(a)*length(b);
        if (d == 0)
        {
        	angle = 0;
        }
        else
        {
        	c = x / d;
        	angle = acos(c)*180/pi;
        }
        return angle;
}