forcing function execution as a core function or from a certain package

[Sergei Steshenko]

Hello,

suppose there is a 'foo' function which exists in several places. E.g. it may 
exist as a core Octave function and in a number of loaded packages.

Is there a way to explicitly tell Octave which function is meant without 
unloading the packages ?

For example, 'sumsq' exists as both part of nan-2.5.5 package and as Octave 
built-in function.

Thanks,
  Sergei.


P.S. 'sumsq' in this case appears to do the same thing as part of nan-2.5.5 
package and as Octave built-in function, but its help message from nan-2.5.5 
does not correspond to its code and does not correspond to help message of the 
Octave core function.