Re: non-linear curve fitting with 3 independent variables - suggest a software in Linux

anandram@xxxxxxxxx wrote: 
Hello,

I want to fit a curve of the type

f(x,y,z) = a + b*x + c*y + (d/z + e*x/z + f*y/z);

to the dataset listed at the end of the post.

Is there any curve fitting program available in Linux to automate this?

I tried to use GNUPLOT but I think it does not handle more than 2
independent variables.

It would be nice if there is a script like language in that softaware
to fit the curve since I have more than 100 datasets like this.

/// DATASET
x   y    z    f(x,y,z)
1 1.88 0.3666 1.090e-10
1 1.96 0.3978 1.165e-10
1 2.08 0.351 1.147e-10
1 2.16 0.3822 1.244e-10
11 1.8 0.4134 4.724e-11
11 1.92 0.3666 4.675e-11
11 2 0.3978 4.913e-11
11 2.12 0.351 5.116e-11
11 2.2 0.3822 5.569e-11
21 1.84 0.4134 4.591e-11
21 1.96 0.3666 4.531e-11
21 2.04 0.3978 4.798e-11
21 2.16 0.351 5.039e-11
31 1.8 0.3822 4.257e-11
31 1.88 0.4134 4.582e-11
31 2 0.3666 4.512e-11
31 2.08 0.3978 4.887e-11
31 2.2 0.351 5.101e-11
41 1.84 0.3822 4.308e-11
41 1.92 0.4134 4.604e-11
41 2.04 0.3666 4.535e-11
41 2.12 0.3978 5.034e-11
51 1.8 0.351 4.051e-11
51 1.88 0.3822 4.365e-11
51 1.96 0.4134 4.635e-11
51 2.08 0.3666 4.610e-11
51 2.16 0.3978 5.175e-11
61 1.84 0.351 4.110e-11
61 1.92 0.3822 4.417e-11
61 2 0.4134 4.671e-11
61 2.12 0.3666 4.785e-11
61 2.2 0.3978 5.295e-11
71 1.88 0.351 4.185e-11
71 1.96 0.3822 4.463e-11
71 2.04 0.4134 4.726e-11
71 2.16 0.3666 4.954e-11
81 1.8 0.3978 4.233e-11
81 1.92 0.351 4.252e-11
81 2 0.3822 4.505e-11
81 2.08 0.4134 4.867e-11
81 2.2 0.3666 5.093e-11
91 1.84 0.3978 4.318e-11
91 1.96 0.351 4.305e-11
91 2.04 0.3822 4.555e-11
91 2.12 0.4134 5.057e-11
101 1.8 0.3666 4.077e-11
101 1.88 0.3978 4.394e-11
101 2 0.351 4.350e-11
101 2.08 0.3822 4.648e-11
101 2.16 0.4134 5.218e-11

Thanks for your help
Anand

You could do it with Excel using the multiple regression function.
.

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