if the discrete values have a regular spacing you can do it with (assuming a spacing of 5):

do for [t=0:50:5] { ... }

If you have specific values in mind it works with

do for [t in "0 4 18 50"] { ... }

I haven’t tested it, but I should be possible in a similar way I did it in the U.S. states post. You can store the values of your parameters in a string variable and then indexing the string. I don’t know if it is the best method to do it, but it should work. Here is an code example (which I have not tested):

f(x) = a*x+b
A = []
B = []
do for [n=1:400] {
   file = sprintf('data%03.0f',n)
   fit f(x) file via a,b
   A = A.sprintf(%f,a)
   B = B.sprintf(%f,b)
}
plot for [n=1:400] '+' u (n):(A[n:n]), for [n=1:400] '+' u (n):(B[n:n]) 

I have the 400 files containing x,y data named as data001, data002, …, data400. I want to make a curve fitting in each file and plot the value of the parameters as a function of the file index.

Could you help me with that?

Thank you

Even better would be this one:

if(y(x)== 0) gg(x) = v1(x)

But it seems the “if” functions do not work with functions as will as
this:

gg = f(x)

thanks for your help.
Cheers.
keghn

y(x) = 0.5*m1*x**2 + 0.5*m2*v3(x)**2 + 0.5*i* w(x)**2 - 0.5*m1*v1**2
gg(x) = y(x)==0 ? 4 : 0

I do these lines in a script:

y(x) = 0.5 * m1 * x**2 + 0.5 * m2 * v3(x)**2 + 0.5 * i * w(x)**2 – 0.5 * m1 * v1**2
if( y(x) == 0) then gg = 4

and get:

gnuplot> load ‘0s.p’
“0s.p”, line 57: undefined variable: x
the error is on the “if” line:

Is their a way to to this in gnuplot.

Thank for any help,

keghn