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Groups > comp.graphics.apps.gnuplot > #2758

fit two variables to a complex function

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Hi,
I'm trying to fit a two parameter complex f(freq,temp) function to a dataset. Since I know that I can't really use complex-valued functions I'm following the advice I found on line: I split my data file so that I have the first dataset on the file be the real part and the second the imaginary part. My problem is that all the examples on the web use the second argument on the function to switch between the real and the imaginary functions to fit, so I'm not sure if it is even possible. I tried to use the column function like so:

f2(x,t) = ((column(-2)%2)==0) ? Re_f(x,t) : Im_f(x,t)

but I get, not completely unexpectedly:

fit f2(x,y) DATAFILE every ::9 using 1:2:9:11 via A0
column() called from invalid context

if, stretching some of the examples, I try:

f2(x,t,z) = (z==0) ? f(x,t) : phi(x,t)
fit f2(x,y,z) DATAFILE every ::9 using 1:2:-1:9:11 via A0

I get:

undefined variable: z

Any ideas?

Thanks

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fit two variables to a complex function lamr64@gmail.com - 2015-02-18 16:36 -0800
  Re: fit two variables to a complex function Karl <mail.kfr@gmx.net> - 2015-02-19 16:24 +0100
    Re: fit two variables to a complex function Karl <mail.kfr@gmx.net> - 2015-02-19 16:36 +0100
    Re: fit two variables to a complex function Karl <mail.kfr@gmx.net> - 2015-02-19 17:30 +0100
      Re: fit two variables to a complex function luis <lamr64@gmail.com> - 2015-02-19 15:38 -0800
      Re: fit two variables to a complex function Karl <mail.kfr@gmx.net> - 2015-02-25 23:59 +0100

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