Help writing a simple function

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Kristopher
Kristopher on 20 Jun 2014
Edited: per isakson on 17 Sep 2017
I'm new to functions, and I was wondering how you would write a simple if, then function.
if x<4, then f(x)=-1
if 4<=x<=4 then f(x)=cos(x)
if x>4 then f(x)=1
%when an x is entered, it should give f(x) as the output. %Thank you.

Answers (3)

Azzi Abdelmalek
Azzi Abdelmalek on 20 Jun 2014
Read the documentation, you will find examples if, elseif, else

David Sanchez
David Sanchez on 20 Jun 2014
You should do as Azzi Abdelmalek says, anyway, here is your code:
if x<4
f = -1;
elseif x>=4 && x<=4
f = cos(x);
else
f = 1;
end

Andrei Bobrov
Andrei Bobrov on 20 Jun 2014
Edited: Andrei Bobrov on 20 Jun 2014
function out = f(x)
out = sign(x-4);
out(~out) = cos(4);
end
use
>> out = f([- 3 5 6 4 -2 3 1 4])
out =
-1.00000 1.00000 1.00000 -0.65364 -1.00000 -1.00000 -1.00000 -0.65364

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