How to set a variable line width when plotting?

Question

I would like to plot a curve with a variable line width. I normally would do the following if I wanted to use points instead of a line:

gnuplot> plot 'curve.dat' u ($1):($2):($1) ps var

where curve.dat is filled with:

0  0
1  1
2  4
3  9
4  16
5  25

and so on. Now if I try something similar for the line width:

gnuplot> plot 'curve.dat' u ($1):($2):($1) lw var

I get the error message:

undefined variable: var

Or is this something that cannot be done with gnuplot?

Answer 1

You're right that linewidth doesn't accept var like pointsize does. But you can have a similar effect by using filledcurves:

WIDTH_FACTOR=20
plot 'curve.dat' u ($1):($2+$1/WIDTH_FACTOR):($2-$1/WIDTH_FACTOR) w filledcurves