Thank you kind gentlemen for helping me move forward with modern APL.
Am I correct in assuming that expressions such as {⍬≡0⍴⍵} are lambdas?
And that the symbols theta and omega are place holders similar to X and Y in a 
user defined function?
(all new stuff to me BTW - but very interesting.)

respect

Peter
On 2014-07-31, at 9:51 PM, Elias Mårtenson <loke...@gmail.com> wrote:

> This is the table I have included in the Emacs mode documentation. I got the 
> information from the ISO spec, so I hope it's correct:
> 
>   0   (1-R⋆2)⋆0.5
>  ¯1   arcsin R               1   sin R
>  ¯2   arccos R               2   cosin R
>  ¯3   arctan R               3   tan R
>  ¯4   (R+1)×((R-1)÷R+1)⋆0.5  4   (1+R⋆2)⋆0.5
>  ¯5   arcsinh R              5   sinh R
>  ¯6   arccosh R              6   cosh R
>  ¯7   arctanh R              7   tanh R
>  ¯8   -(¯1-R×2)⋆0.5          8   (¯1-R⋆2)⋆0.5
>  ¯9   R                      9   Real part of R
> ¯10   +R                    10   |R
> ¯11   0J1×R                 11   Imaginary part of R
> ¯12   ⋆0J1×R                12   Arc R
> 
> Regards,
> Elias
> 
> 
> On 1 August 2014 06:46, David B. Lamkins <dlamk...@gmail.com> wrote:
> Reshape your datum as an empty vector then match to zilde. If the match
> succeeds then your datum is a number; otherwise a character/string.
> 
> I believe that there's a circle function to extract the imaginary part
> of a number, if any. You can test for a nonzero imaginary part.
> 
> Finally, you can compare a number's floor to the number itself to
> determine whether the value is integer or real.
> 
> Not knowing your application, I have to warn you that you shouldn't use
> these tests to infer anything about APL's storage. All of the numeric
> tests are subject to quad-CT.
> 
> On Thu, 2014-07-31 at 15:54 -0400, Peter Teeson wrote:
> > I feel pretty stupid.
> > Looked in the APL2 IBM manual but do not understand how to determine the 
> > data type of a variable.
> > Neither the primitives nor the Quads sparked the answer in my brain.
> > It must be something pretty obvious but not to me right now.
> >
> > So if I have a function FOO X how do I determine if X is character, 
> > integer, float, or imaginary?
> > Assuming that it is not a nested array of course.
> >
> > respect…
> >
> > Peter
> >
> 
> 
> 
> 

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