/* Improved v2Len function */

#include "vector2.h" /* For the vector structure declaration */
#include <math.h>    /* For sqrt, sin, cos & atan2 functions */

#include <float.h>
float v2Len(vector2 v) {                    /* Length of vector */
    float a = fabs(v.x), b = fabs(v.y), c;  /* absolute values */
    if (b > a) {                            /* wrong one larger ? */
        c = b; b = a; a = c;                /* exchange */
    }                                       /* Now a is larger */
    if (a == 0.0) {
        return a;                           /* Both components are zero */
    }
    b /= a;                                 /* compute b/a */
    if (b < FLT_EPSILON) {
        return a;                           /* Answer very close to a */
    }
    return a * sqrt(1.0 + b*b);             /* full Pythagoras' rule */
}


/********* test main *********/
#include <stdio.h>
main () {
    vector2 a = {0.7*FLT_MAX, 0.7*FLT_MAX},
            b = {1, FLT_EPSILON*0.1},
            c = {FLT_MIN, FLT_MIN};
    float d, e, f;
    d = v2Len(a);
    e = v2Len(b);
    f = v2Len(c);
    printf("v2Len(a) = %g - should be a bit below %g\n", d, FLT_MAX);
    printf("v2Len(b) = %g - should be 1\n", e);
    printf("v2Len(c) = %g - should be about %g\n", f, FLT_MIN*1.414);
    return 0;
}