Choose a function using a switch statement.

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Hi, I am trying to create a switch function that will allow the user to choose to run one of two functions. Here is what I have :
function stressstrain
result = ...
input('For Plane Stress press 1, for Plane Strain press 2 and then press enter \n');
switch result
case 1
case 2
otherwise disp
('You pressed an unspecified key, please run again')
end
end
Is it possible to call and run a function using the case command ?
Apologies if this is a poorly worded and trivial question, I have only limited experience of matlab, but have an assignment due in very soon ! Thanks, Joshua
  2 Comments
jo brown
jo brown on 5 Apr 2015
Yes, I tried ! But I'm a novice and have very limited experience of matlab.

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Answers (2)

John D'Errico
John D'Errico on 4 Apr 2015
Edited: John D'Errico on 4 Apr 2015
It looks like you are almost there, so here is an example of a switch construct that will call two different functions randomly.
switch round(rand(1))
case 0
x = cos(57);
case 1
x = sin(eps);
otherwise
% of course, we can't get into this otherwise branch
% given the way I generated the switch argument, so I
% could have left it out completely.
disp('the sky is falling!')
end
  1 Comment
jo brown
jo brown on 5 Apr 2015
Nope, I don't get it :(
I have two variations of a function that I need to allow a user to call. Specifically, its the syntax after the case statement that I am not sure of.
I'll keep trying, but would appreciate any further help.

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jo brown
jo brown on 5 Apr 2015
Edited: John D'Errico on 5 Apr 2015
I think I got it ! How does this look ?
function stressstrain
result = input('For Plane Stress press 1, for Plane Strain press 2 and then press enter \n');
switch result
case 1
run PStress
case 2
run PStrain
otherwise disp ('You pressed an unspecified key, please run again')
end
  3 Comments
jo brown
jo brown on 5 Apr 2015
Hey John, thanks for your input. It seems to work either way, but I guess less code is better.
John D'Errico
John D'Errico on 5 Apr 2015
Yep. Run works there, and will give the identical results, with or without. So I suppose I should test to see if there is a time cost for using run. Does run add extra overhead? Let us see...
I've created a simple script, that does essentially nothing interesting.
type testscript
a = 2;
b = a+3;
tic
for i = 1:100000
testscript
end
toc
Elapsed time is 1.357657 seconds.
So 100000 calls to testscript took a bit over 1 second. Now I'll re-run the test using run in there.
tic
for i = 1:100000
run testscript
end
toc
Elapsed time is 167.432911 seconds.
So there IS a significant cost to the use of run. Not truly massive per execution, taking roughly an extra 0.0017 seconds per execution of run.
(167.43 - 1.36)/100000
ans =
0.0016607
A few CPU cycles here, a few there, and eventually it still all adds up to not that much, unless you will be using run a few millions of times.

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