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Re: matrix operation [message #74072]

Tue, 28 December 2010 12:09

rogass
Messages: 200
Registered: April 2008

Senior Member

On 23 Dez., 17:08, Gray <grayliketheco...@gmail.com> wrote:
> On Dec 23, 10:50 am, Paolo <pgri...@gmail.com> wrote:
>
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>> For large values of N, the methods you mentioned are likely
>> to be slower then a simple addition/multiplication combo.
>
>> x'=a1*x+b1*y+c1*z+d1
>> y'=a2*x+b2*y+c2*z+d2
>> z'=a3*x+b3*y+c3*z+d3
>
>> Ciao,
>> Paolo
>
>> On Dec 23, 9:39 am, Gray <grayliketheco...@gmail.com> wrote:
>
>>> Hi all,
>
>>> I'm just getting really confused about how to do this properly. Can
>>> you all help?
>
>>> I have a list of x y coordinates, and I want to perform an affine
>>> transformation on them, so I have a 3xN array of (xi,yi,1) and a 3x3
>>> matrix for my transformation, and I want to end up with a 3xN array of
>>> (x'i,y'i,1). How can I transform all my coordinates at once? I know
>>> my tools are #, ##, transpose/reform, and matrix_multiply, but I seem
>>> to be chronically unable to sort this out. Thanks!
>
>>> --Gray
>
> Well... I guess that makes sense. :)

Hi,
are the inbuilt routines like t3d, poly_2d and /or poly_warp not
useful? Did they crash for large matrices?

Cheers

CR

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[Message index]

		Re: matrix operation By: rogass on Tue, 28 December 2010 12:09
		Re: matrix operation By: Gray on Thu, 23 December 2010 08:08
		Re: matrix operation By: pgrigis on Thu, 23 December 2010 07:50

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