gnuplot-beta

how to plot function in a certain range?

[Dr. H. E. <eh...@ip...>]

I have a single plot with x ranging from [0:100] and data points in that
interval. Then I want to add a function f(x) , which describes the data
only in a limited interval, e.g. [0:50]. How do I add the function with
that range to the plot? If I try "plot [0:50] f(x), data" gnuplot will
always change the x range of the whole plot and I cannot see the data from
[50:100].




-- 
Dr. Hartmut Ehmler
W7-X Magnets and Cryostat
currently at CEA, Saclay (France)
0033-169085706

Re: how to plot function in a certain range?

[Daniel J S. <dan...@ie...>]

Dr. Hartmut Ehmler wrote:
> I have a single plot with x ranging from [0:100] and data points in that
> interval. Then I want to add a function f(x) , which describes the data
> only in a limited interval, e.g. [0:50]. How do I add the function with
> that range to the plot? If I try "plot [0:50] f(x), data" gnuplot will
> always change the x range of the whole plot and I cannot see the data from
> [50:100].

Try using the ternary operator as part of your function definition (help ternary).  Define the support in the range of [0,50], e.g.,

f(x) = x<0 && x>50 ? 1/0 : <function definition>

(If you want the function to actually be zero outside its support, replace 1/0 with 0.)

Then try plotting with range [0:100]

Dan

Re: how to plot function in a certain range?

[<br...@ph...>]

Dr. Hartmut Ehmler wrote:
> I have a single plot with x ranging from [0:100] and data points in that
> interval. Then I want to add a function f(x) , which describes the data
> only in a limited interval, e.g. [0:50]. How do I add the function with
> that range to the plot? If I try "plot [0:50] f(x), data" gnuplot will
> always change the x range of the whole plot and I cannot see the data from
> [50:100].

Parametric mode is the generic answer to this kind of problem:

	set parametric
	set trange [0:50]
	plot 'data', t, f(t) title "f(x)"