Re: [Gnuplot-info] Problem with singularity <-> Divide by zero

[Thomas S. <t.s...@fz...>]

the formula for differential cross section of rutherford scattering is
dsigma/dOmega ~ 1/(sin(theta/2)**4)
this function can not have the shape you've drawn in your graph.
it *is* infinite at x=0.

the reason not to take the data point at x=0 into account, is that all
non-scattered particles go under zero degree, but you are interested
in scattered particles only, i.e. those particles which are described by
the above formula.

i don't see anything wrong with your data and your fit as it is.


Hans-Bernhard Bröker-2 wrote:
> 
> DonBieber wrote:
> 
>> I have data concerning rutherford-scattering. In order to verify the
>> formula
>> I need to make a fit with the function f(x)=a*1/(sin(x/2)**4). Like you
>> can
>> see I get for x=0 a little mathematical problem. The following picture
>> shows
>> the fit in green and how I would like it to be in blue. Is there any
>> possibility of telling GnuPlot to skip x=0 and interpolate? 
> 
> Throw away the data point at x=0 (and all other exact multiples of \pi, 
> of course) before you pass the data to the 'fit' command.
> 
> 
> 
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