Isqrt (integer square root) of X: Difference between revisions

But for those whom only the quadratic residue algorithm will do, just substitute this form offor the ISQRT() function in the previous example. (The output is identical.) But be warned: there is a bug lurking in the algorithm as presented in the task description. The statement q := q * 4 in the first while loop will overflow the limits of ALGOL-M integer data type (-16,383 to +16,383) for any value of x greater than 4095 and trigger an endless loop.

Q := Q * 4; % WARNING: POSSIBLE OVERFLOW! %