# draw a plot-graph

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andreas kaffas on 18 Oct 2020
Commented: andreas kaffas on 18 Oct 2020
how can i draw a graph from this equation:F(n) = x2^3 − 3x1^2 + x3 ?
Can anyone explain?
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andreas kaffas on 18 Oct 2020
thank you....there was a problem with the exercise and teachers uploaded another file in which the variables are defined!!

madhan ravi on 18 Oct 2020
doc fimplicit3
##### 2 CommentsShowHide 1 older comment
andreas kaffas on 18 Oct 2020
thank you....there was a problem with the exercise and teachers uploaded another file in which the variables are defined!!

Walter Roberson on 18 Oct 2020
If F(n) is not a constant, then you have the problem that you have three independent variables and one dependent variable. That would require 4 dimensional plots.
The closest you can get to 4 dimensional plots is to use isosurface() or slice() .
For example:
Fn = @(x1, x2, x3) x1.^2 - 2*x2.^3 + 3*x3/5 + 4;
[X1, X2, X3] = meshgrid(linspace(-2,2,25));
Z = Fn(X1, X2, X3);
for level = -13:5:25; isosurface(X1, X2, X3, Z, level); end
andreas kaffas on 18 Oct 2020
thank you....there was a problem with the exercise and teachers uploaded another file in which the variables are defined!!