Octave: Loaded package is not recognized

Question

I have installed package image via pkg install -forge image and after tons of warnings (I am using clang as a C compiler, yeah, I know...) it finished installing.

I then loaded the package with ordinary pkg load image and Octave did not complain. But when I typed help viscircles to get some help on the function, Octave behaved like there was no package image , meaning it returned

>> help viscircles
error: help: the 'viscircles' function belongs to the image package 
from Octave Forge but has not yet been implemented.

Please read <http://www.octave.org/missing.html> to learn how you can
contribute missing functionality.

Now I executed the pkg list to see if the package was indeed installed and loaded and yes, it was (there was an asterisk next to image package, which indicates that the certain package is loaded).

I decided to unload all packages and so I did. Now, before loading image again, I executed help viscircles again, but this time I got the next error:

>> help viscircles
error: help: the 'viscircles' function belongs to the image package 
from Octave Forge which you have installed but not loaded.  To load the 
package, run 'pkg load image' from the Octave prompt.

Interesting... I loaded the package again and same problem as before. I also downloaded the package manually and reinstalled it, same problems.

And yes, I have Octave 4.0.2, the requirements for image 2.6.2 is version 4.0.0+.

Answer 1

The function viscircles is on development versions of the image package only. It is not part of the current release, version 2.6.2 which you have installed.

The error message:

>> help viscircles
error: help: the 'viscircles' function belongs to the image package 
from Octave Forge which you have installed but not loaded.  To load the 
package, run 'pkg load image' from the Octave prompt.

means that the function is not part of Octave and if it is to exist at all, it will be on the image package. It doesn't mean that the image package will actually have it, only that it belongs to it. The error message you get after loading the package:

>> help viscircles
error: help: the 'viscircles' function belongs to the image package 
from Octave Forge but has not yet been implemented.

Please read <http://www.octave.org/missing.html> to learn how you can
contribute missing functionality.

tells you the issue. The function viscircles is not implemented on that version of the package.

You can get it from the mercurial repository of the image package though at 75df28049249 . Not sure if it will work on Octave 4.0 though.