Re: Problem with arcs in gpic

[Werner LEMBERG]

> Following up on my own report after poking through things this
> morning.  In the src/preproc/pic directory, in file object.cpp, in
> the routine declared as "linear_object *object_spec::make_arc",
> lines 1833 and 1834 have the statement
>
>     while (radius < d)
>       radius *= 2.0;
>
> In my example, in some cases the test (radius < d) was satisfied,
> but the difference in the two values was on the order of 1e-10.
> Since radius was 0.1, doubling the radius leads to the fairly gross
> error that I was encountering.  For the time being, my workaround is
> to replace that statement with
>
>     if (radius < d)
>       radius = d;
>
> which fixed my problem.  The original code appears to have been
> intended to deal with the situation when radius is orders of
> magnitude less than d.  My replacement code simply assigns radius
> the smallest value that avoids problems with the floating point
> code/libraries further on in the routine.

Your fix sounds reasonable.  Thanks for the analysis!  I don't see any
reason at all why there is this loop.  In case noone objects I'll
apply your change within a few days.


    Werner