Weird Function TRIANGULATE in IDL

Time to update my blog again. It’s been more than a year since my last update after all. Today I encountered with a weird error in IDL when trying to improve computation precision of own polar transform image routines. The source was traced back to function TRIANGULATE. So far I really have no idea about why it occurs. The example is as follows:

IDL> theta=dindgen(360L)
IDL> rad=dindgen(500L)
IDL> xpol=rad#cos(theta/1.8d2*!dpi)
IDL> ypol=rad#sin(theta/1.8d2*!dpi)
IDL> triangulate,xpol,ypol,tri
% TRIANGULATE: Points are co-linear, no solution.
% Execution halted at: $MAIN$

However, if I type the following TRIANGULATE works flawlessly:

IDL> xpol=rad#cos(float(theta/1.8d2*!dpi))
IDL> ypol=rad#sin(float(theta/1.8d2*!dpi))
IDL> triangulate,xpol,ypol,tri
IDL> help,tri
TRI             LONG      = Array[3, 358920]

This is really annoying, as I can’t figure out how come co-linearity can be related to float or double precision whatsoever. Not sure if anyone could help this for me, but I just throw this problem here and see if there’s anyone else faced with the same encounter so that we can potentially sigh together…

Advertisements
Weird Function TRIANGULATE in IDL

One thought on “Weird Function TRIANGULATE in IDL

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

w

Connecting to %s