[metapost] Hello: possible error in MetaPost tutorial

Shriramana Sharma samjnaa at gmail.com
Tue Mar 6 12:39:16 CET 2012

Hello I'm new to TeX/Metapost. In fact I'ven't even started using them
yet but planning to do so for a font project. I'll be having highly
noob questions (but I will make best attempts to do my homework before
asking). I request the kind help of the people here. Thanks.

So I was looking at:
http://www.tlhiv.org/MetaPost/tutorial/tutorial.html where it says:

"In mathematics as in MetaPost, the positive sense of rotation is
counterclockwise. Thus the red halfcircle is obtained (from the black
one) by a rotation of -90 degrees, whereas the blue halfcircle is
obtained by a rotation of 90 degrees. "

But the red circle is actually rotated by anticlockwise rotation and
the blue circle by clockwise rotation. Thus the sign of the values
should be reversed. Even the commands read:

  draw halfcircle scaled 2u rotated 90 shifted (1.5u, 4u) withcolor red;
  draw halfcircle scaled 2u rotated -90 shifted (1.5u, 3u) withcolor blue;

I hope I'm right. I found a mail ID for the author and am cc-ing to
them too, in (the unlikely) case that they are not on the list.

Shriramana Sharma

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