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Blitz Support : |
From: carlos.rega_at_[hidden]
Date: 2004-08-04 11:04:11
John McHenry <john_d_mchenry_at_[hidden]>
Sent by: blitz-support-bounces_at_[hidden]
02/08/2004 01:57
Please respond to Support list for Blitz++
To: blitz-support_at_[hidden]
cc:
Subject: [Blitz-support] Matlab-like stuff
> Hi there:
>
> I want to know if I can do some simple Matlab stuff with blitz like
these Matlab examples,
>
> N = 10000;
> A = [7:N]; % create a length N-6 array
>
> How do you do it in blitz?
This one is easy:
int N = 10000;
Array<float,1> A(Range(1,N-6));
A = tensor::i+6;
the tensor::i is an index placeholder, check the manual for that, that
allows you to write expressions with blitz objects in the same way you
would with tensors on paper, it is described in the manual.
>Then there's this example,
>
>M = [1:4; 5:8; 9:12]
>M =
> 1 2 3 4
> 5 6 7 8
> 9 10 11 12
I would do this one as follows:
Array<float,2> M(Range(1,3),Range(1,4));
M = 4*(tensor::i-1)+tensor::j;
as you see, i in the first index, j the second and so on, in the manual it
explains how to do this sort of things in more detail, so as long as you
can write M(i,j) as an expresion of i and j you are done.
>M(1,1:3) = [3:-1:1]
>M =
> 3 2 1 4
> 5 6 7 8
> 9 10 11 12
I am not sure about this one, perhaps someone with more experience in
blitz can help? I would just use the same method as above and then change
the first row by hand.
Hope this helps
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