[metapost] Update on mpost 2013 bug

[Michael D. Godfrey]

> I have found a failure in the mpost which is installed with texlive-2013
> and with 2012. The last correct mpost appears to be from texlive_2010.
> Attached are:
>
> 1. The mpost script to be processed by mpost and mptopdf in figs-2.mp
>     Note that this requires -numbersystem=double
>
> 2. The correct output in figs-2.pdf
>
> 3. The incorrect output in figs-2-2013.pdf
>
> The problem is that the tapered sin and cos functions disappear.
> I tried a number of changes to the code, but could not make it work.
>
> I will try the latest tar file and tell you if it works or not.
>
> Michael
>
>
I installed texlive 2010 and it works correctly. Note that mpost
form 2010 compiles this function without need of double option.
It has none anyhow.

I very much hope that you can fix this. I have used TeX and its associated
stuff since about the beginning and this is the first update 
incompatibility that
I have encountered. Luckily, just before posting the paper with that figure
in it, I caught the error.

Michael