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

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/ghihookwgzxculshibyc@forum.dlang.org).  You don't need this for most practical applications, though.

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

in addition to what sarn said, tan(3pi/4) is a pole, not infinity. the mean of the left and right hand limits is 0

On Monday, 7 August 2017 at 04:47:56 UTC, Nicholas Wilson wrote:
> 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
>
> in addition to what sarn said, tan(3pi/4) is a pole, not infinity. the mean of the left and right hand limits is 0

Thanks for the help. I will appreciate any resources for further reading