How to define a piecewise anonymous function

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Stephan
Stephan on 31 May 2019
Commented: Star Strider on 16 May 2020
Hello everyone,
the example code
syms x
continuous_function = x^2+x;
matlabFunction(continuous_function,'Vars',x)
gives me the anonymous function
@(x)x+x.^2
I would like a similar result for piecewise functions. However, the code
syms x
piecewise_function = piecewise( 0<x<1, x, 'otherwiseVal', 0 );
matlabFunction(piecewise_function,'Vars',x)
does not work.
Thanks for any help!

Accepted Answer

Star Strider
Star Strider on 31 May 2019
You need to use ‘logical indexing’:
piecewise_function = @(x) (x.^2+x) .* ((0<x) & (x<1));
x = linspace(-1, 2);
figure
plot(x, piecewise_function(x))
producing:
How to define a piecewise anonymous function - 2019 05 31.png
  6 Comments
Star Strider
Star Strider on 16 May 2020
ElPerroVerde — My pleasure!
A Vote would be appreciated!
.

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More Answers (1)

Walter Roberson
Walter Roberson on 16 May 2020
If you use matlabFunction with 'file' option, then it will convert piecewise() into if/else in the generated code.
Note: because it uses if/else instead of logical indexing, the generated code will not be vectorized on that variable.

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