Hi Bo,
Shouldn't it be:
rou =: _1^2*i.%]
((_1^2%])-:[: r. 2p1 * i. % ]) 5
0
Hallo Bo Jacoby, je schreef op 06-01-11 10:26:
> The page
> http://www.jsoftware.com/jwiki/JohnRandall/FourierTransformAndPolynomialMultiplication
> contains the definition
> rou=:[: r. 2p1 * i. % ]
> I'd like to supplement with the shorter definition
> rou=:_1^2%]
> but the page is write protected. Why?
> - Bo
>
> --- Den tors 6/1/11 skrev Roger Hui<[email protected]>:
>
>> Fra: Roger Hui<[email protected]>
>> Emne: [Jprogramming] FFT
>> Til: "Programming forum"<[email protected]>
>> Dato: torsdag 6. januar 2011 07.54
>> http://www.jsoftware.com/jwiki/Essays/FFT
>>
>> cube =: ($~ q:@#) :. ,
>> roots =: +...@]^:(0>[) (_1^2%]) ^ i...@-:
>> floop =: 4 : 'for_r. i.#$x do. (y=.{."1 y) ] x=.(+/x)
>> ,&,:"r (-/x)*y end.'
>> fft =: (] floop&.cube 1&ro...@#)
>> f. :. ifft
>>
>> This is a rare practical use of a high rank array.
>> ("High" means greater than 4, say.) The only other
>> "use" that I know of is the complete tensor of order n.
>> http://www.jsoftware.com/help/dictionary/dccapdot.htm
>>
>> The expression ,&,:"r in floop can be simplified to
>> ,:"r
>> if r is nonzero. This suggested that perhaps the
>> definition
>> of atom0 ,: atom1 is incorrect. (Should have shape 2
>>
>> instead of 2 1.)
>>
>>
>>
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--
Met vriendelijke groet,
=@@i
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