From: "baptiste Auguié" <ba208@...>
Date: 2007-07-01T19:43:01+09:00
Subject: simple math operations on arrays

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Hi,

Again a very basic problem, I need to create arrays with numerical  
values, and do *very simple* math operations on each elements. I've  
tried to install ruby-gsl as suggested but I don't have admin rights  
on the machine. Here is my try:

> radius=0.045
> aspectRatio=[]
> longAxis=[]
> shortAxis=[]
>
> 0.5.step(1, 0.1) { |x| aspectRatio << x.to_s }
>
> longAxis=aspectRatio.collect{ |x|  radius.to_f*((x.to_f)**(-2/3)) }
> aspectRatio.each_index { |x| shortAxis << longAxis 
> [x].to_f*aspectRatio[x].to_f}
> puts longAxis
> puts shortAxis


the result is wrong, and it all seems over-sophisticated to me. I  
must have missed a basic technique.

I need three arrays: 'aspectRatio' is just [0.5, 0.6, 0.7, 0.8, 0.9,  
1.0], but I want to construct it as a range (call me lazy). The  
second is constructed doing the same calculation on every element of  
'aspectRatio'. The third one needs to access elements of the same  
index from the previous two arrays, and multiply them together to  
form the new array.

Here is the result I'd expect:

> longAxis =
>
>    0.071433
>    0.063257
>    0.057080
>    0.052218
>    0.048274
>    0.045000
>
> shortAxis =
>
>    0.035717
>    0.037954
>    0.039956
>    0.041774
>    0.043447
>    0.045000

and the result I get:

> 0.09
> 0.075
> 0.0642857142857143
> 0.05625
> 0.05
> 0.045
>
> 0.045
> 0.045
> 0.045
> 0.045
> 0.045
> 0.045

Any help / advice appreciated,

Best regards

baptiste



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