Hi,

That's correct, since PHP cos() and sin() uses radians and not degrees.
This can be solved by first using deg2rad(). This would make your code
look like this:

<code>
  $i = deg2rad(270);
  print "cos:".cos($i);
  print "sine:".sin($i);
</code>
<display>
  cos:0
  sin:-1
</display>

/Johan

Bradley J Bristow-Stagg wrote:
> 
> Hey guys,
>   I am currently dabbling in a little graphics generation with gd_lib in PHP
> on my Win2K box with IIS 5.  Up until now I have had ZERO problems and am
> really loving working with PHP.  My problem then?  Well I am rotating a
> polygon around a point and PHP is not giving me correct values for cos() and
> sine().. Some sample code and values follow:
> 
> <code>
>   print "cos:".cos(270);
>   print "sine:".sine(270);
> </code>
> <display>
>   cos:0.9843819506325
>   sin:-0.17604594647121
> </display>
> 
>   What's wrong with this picture?  Well using my trusty scientific
> calculator (from the ol' school days) I get:
>   cosine(270)  = 0
>   sine(270) = -1
> 
>   Without getting correct values for the sine and cosine the rotation
> equations do some really funky stuff =).  So what do I do now?
> 
> Regards
> 
> Bradley J Bristow-Stagg
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