D.12.2.9 jOft

Usage:

jOft(t,k);

Return:

the j-invariant of t

Assume:

t is a complex number with positive imaginary part

Note:

k describes the number of summands being calculated in the power series, 10*k is input for the procedure expo

LIB "atkins.lib";
ring r = (complex,30,i),x,dp;
number t=(-7+i*sqr(7,250))/2;
jOft(t,50);
==> -3375