Re: isa strangeness

[Martin Helm]

Am Montag, 16. August 2010, 04:18:33 schrieb Richard E. Harke:
> I installed octave last night and have been reading the manual
> trying things. (Debian lenny system, installed from debian archive)
> I tried:
> 10> class(10)
> ans = double
> 
> Seems good. Then I tried:
> 11> isa(10, double)
> 
> Invalid call to double.  ......
> 
> which seems like a bug
> 
> Even more curious:
> 12> isa(10, double(10))
> ans = 0
> 
> which seems to say that 10 does not belong to the class it belongs to.
> 
> 13> isa(10, class(10))
> ans = 1
> is correct but hardly seems useful.
> 
> This is not an auspicious start.
> 
> Richard
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The help string of isa is not really good here.
Use 
isa(10, "double") or isa(10, 'double')
class in isa is expected to be a string here which contains the class name.
The reason is the syntax
isa(10, double) 
will treat double as a function call without arguments, which is a syntax 
error.
- mh