[SciPy-user] lstsq

Gregor Hagelueken gh50@st-andrews.ac...
Thu May 8 10:06:10 CDT 2008


Bruce Southey wrote:
> Gregor Hagelueken wrote:
>   
>> Hi,
>>
>> I would like to use lstsq to fit a curve y using a simple linear 
>> combination of three spectra (spectrum1-3 see below). Since the 
>> program below always crashes, I played around with it and found that 
>> it does not crash if I copy the contents of the array "spectrum2" to 
>> the array "spectrum3" (using spectrum3[0:36]=spectrum2[0:36]). But as 
>> soon as I change one of the numbers in array "spectrum3" it crashes again.
>>
>> What is the mistake?
>>
>> Thanks,
>> Gregor
>>
>> from numpy import *
>> from numpy.random import normal
>> from pylab import *
>>
>> t = arange(205, 241, 1.0)
>>
>> #spectrum1
>> spectrum1=array([-25.35,-30.85,-34.6,-36.5,-36.75,-35.95,-35.2,-34.2,-33.6,-33.55,-33.8,-34.2,-34.2,-34.8,-35.4,-36.25,-36.6,-36.85,-36.55,-35.85,-35.05,-33.55,-31.7,-29.6,-27.15,-24.1,-21.5,-18.95,-16.4,-13.85,-11.45,-9.43,-7.76,-6.24,-4.81,-3.88])
>> #spectrum2
>> spectrum2=array([8.08,5.37,1.24,-3.07,-6.02,-8.84,-11.2,-13.05,-14.85,-17.75,-17.5,-18,-18.35,-18.65,-18.15,-17.45,-17.15,-16.3,-15,-13.15,-11.57,-9.76,-7.98,-5.79,-3.73,-2.37,-0.61,0.08,0.15,1.17,0.73,0.77,0.38,0.56,0.28,0.64])
>> #spectrum3
>> spectrum3=array([-25.8,-21.45,-18.0,-15.59,-12.82,-10.41,-8.41,-6.58,-4.99,-3.85,-2.62,-1.74,-1.02,-0.5,-0.13,0.17,0.03,-0.08,-0.32,-0.35,-0.48,-0.75,-1.12,-1.31,-1.5,-1.55,-1.17,-1.04,-0.72,-0.46,-0.14,0.21,0.01,0.23,0.03,-0.22])
>>
>> #make curve y
>> y=0.8*spectrum1+0.1*spectrum2+0.2*spectrum3+ normal(0.0, 1.0, len(t))
>>
>> from numpy.linalg import lstsq
>> Nparam = 3
>> A=zeros((len(t), Nparam),float)
>>
>> #helix
>> A[:,0]=spectrum1
>> #beta
>> A[:,1]=spectrum2
>> #coil
>> A[:,2]=spectrum3
>>
>> (p, residuals, rank, s) = lstsq(A,y)
>>
>> #A=p*A
>> #fit = A[:,0]+A[:,1]#+A[:,2]
>> #plot (t, y)
>> #plot (t, fit)
>> ------------------------------------------------------------------------
>>
>> _______________________________________________
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>> SciPy-user@scipy.org
>> http://projects.scipy.org/mailman/listinfo/scipy-user
>>   
>>     
> Hi,
> This works for me on Linux x86_64, Python 2.5 and '1.1.0.dev5133'.
> What are you using and what is the actual error message?
>
> Bruce
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>   
Hi Bruce,

I have a Vista PC (Intel Core2Duo) and Python 2.5 installed.

I do not get any error message, it just hangs up, uses 50% of CPU and 
does not stop again.

Sorry, but I am not sure what you mean by '1.1.0.dev5133'?

Thanks,
Gregor
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