On Sunday, 6 August 2017 at 23:33:26 UTC, greatsam4sure wrote:
import std.math;
import std.stdio;

cos(90*PI/180) = -2.7e-20 instead of zero. I will appreciate any help. thanks in advance.

tan(90*PI/180) = -3.689e+19 instead of infinity. What is the best way to use this module

That's just floating point maths for you. You're not putting exactly pi/2 into cos, just a good floating point approximation. What you're getting out isn't exactly 0, either, just a good floating point approximation. (-2.7e-20 is really, really small.)

Here's a good talk from DConf 2016: https://www.youtube.com/watch?v=97bxjeP3LzY

If you need exact maths, you'll need a symbolic manipulation library (never used one in D, but there was a discussion recently https://forum.dlang.org/thread/ghihookwgzxculshi...@forum.dlang.org). You don't need this for most practical applications, though.

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