#include "map.h"doublecubrt(double a){ double x,y,x1; if(a==0) return(0.); y = 1; if(a<0) { y = -y; a = -a; } while(a<1) { a *= 8; y /= 2; } while(a>1) { a /= 8; y *= 2; } x = 1; do { x1 = x; x = (2*x1+a/(x1*x1))/3; } while(fabs(x-x1)>10.e-15); return(x*y);}
#include "map.h"
double
cubrt(double a)
{
double x,y,x1;
if(a==0)
return(0.);
y = 1;
if(a<0) {
y = -y;
a = -a;
}
while(a<1) {
a *= 8;
y /= 2;
}
while(a>1) {
a /= 8;
y *= 2;
}
x = 1;
do {
x1 = x;
x = (2*x1+a/(x1*x1))/3;
} while(fabs(x-x1)>10.e-15);
return(x*y);
}