defined

[Daniel J S. <dan...@ie...>]

This seems like a bug, even though the syntax is incorrect... but a user might think the syntax is correct if gnuplot doesn't complain but rather returns a non-zero value that will always test positive.

gnuplot> print defined("foo")
141158968
gnuplot> print defined("foo")
141159440
gnuplot> print defined("foo")
141159544
gnuplot> print defined("foo")
141159880
gnuplot> print defined("foo")
141160112
gnuplot> print defined("foo")
141160216


Also, would it be useful to extend defined() from just variables to functions as well?  Say, return 1 if user defined variable, 2 if internal variable, 3 if user defined function, 4 if internal function.

That way, the defined() function could be used inside stat.inc as

if (defined(gamma)!=3) gamma(x) = exp(lgamma_nat(x))

then get rid of these comments like:

# If you have the lgamma() function compiled into gnuplot, you can use
# alternate definitions for some PDFs. For larger arguments this will result
# in more efficient evalution. Just uncomment the definitions containing the
# string `lgamma', while at the same time commenting out the originals.
# NOTE: In these cases the recursive definition for lgamma() is NOT sufficient!

As soon as someone starts uncommenting/commenting code it becomes confusing.


Last, how about an internally defined 'eps' or something similar to represent float machine precision?


Oh, one other thing.  Any interest in a complex version of the gamma function?


Dan