GNUPLOT complex numbers in data file

gnuplot

I have a file with two columns, the first containing purely real numbers and the second containing complex number in a form the GNUPLOT will accept, {a,b} (which is GNUPLOT's equivalent to a + bi). I would like to plot the first column with the absolute value of the second so I tried this:

plot 'data.dat' using 1:abs(2)

This, however, doesn't seem to work. Does anyone know how I can tell GNUPLOT to perform an operation on the data in the dat file before plotting it?

Best Answer

It would save yourself a lot of effort and store your data in three columns, where the second and third denote real and imaginary part.

You can achieve what you are looking for by:

plot "data" using 1:(sqrt($2**2+$3**2))

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Gnuplot: How to plot each line of a data file as Y and incremental X

I found a solution:

plot "data.dat" matrix every 1::1 with linespoint

matix indicates data file type by which the input file interpreted as matrix.
every 1::1 skip the first column

Gnuplot : plotting data from multiple input files in a single graph

You're so close!

Change

plot "print_1012720" using 1:2 title "Flow 1", \
plot "print_1058167" using 1:2 title "Flow 2", \
plot "print_193548"  using 1:2 title "Flow 3", \ 
plot "print_401125"  using 1:2 title "Flow 4", \
plot "print_401275"  using 1:2 title "Flow 5", \
plot "print_401276"  using 1:2 title "Flow 6"

plot "print_1012720" using 1:2 title "Flow 1", \
     "print_1058167" using 1:2 title "Flow 2", \
     "print_193548"  using 1:2 title "Flow 3", \ 
     "print_401125"  using 1:2 title "Flow 4", \
     "print_401275"  using 1:2 title "Flow 5", \
     "print_401276"  using 1:2 title "Flow 6"

The error arises because gnuplot is trying to interpret the word "plot" as the filename to plot, but you haven't assigned any strings to a variable named "plot" (which is good – that would be super confusing).

Best Answer

Related Solutions

Gnuplot: How to plot each line of a data file as Y and incremental X

Gnuplot : plotting data from multiple input files in a single graph

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