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From: | Elias Mårtenson |
Subject: | Re: [Bug-apl] Determining data type... |
Date: | Fri, 1 Aug 2014 10:51:33 +0800 |
Thanks Elias:David used theta as well. Is that also an available symbol?i.e. a greek letter not otherwise used by the APL language?I will have to Google for a good intro to lambdas…They look interesting...respect…PeterOn 2014-07-31, at 10:11 PM, Elias Mårtenson <address@hidden> wrote:Yes, you are right. Here are the available symbols:⍵ - Right-hand argument⍺ - Left-hand argument⍹ - Right-hand function (the lambda is an operator)⍶ - Left-hand function (the lambda is an operator)χ - IndexRegards,EliasOn 1 August 2014 10:04, Peter Teeson <address@hidden> wrote:
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.)respectPeterOn 2014-07-31, at 9:51 PM, Elias Mårtenson <address@hidden> 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 RRegards,EliasOn 1 August 2014 06:46, David B. Lamkins <address@hidden> 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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