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# What is wrong with this expression, why is MATLAB not being able to understand it?

Asked by Yagnaseni Roy on 21 Jun 2012

(50*y).*(28.065*cos(60*t+0.2094395101999999*x)+22.7058*cos(2*(60*t+0.2094395101999999*x))+15.1368*cos(3*(60*t+0.2094395101999999*x))+7.014*cos(4*(60*t+0.2094395101999999*x));

The error given is 'unexpected paranthesis'.

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Answer by Walter Roberson on 21 Jun 2012

You have one more '(' than you have ')'

Count brackets. Each time you encounter a '(' add 1, each time you encounter a ')' subtract 1. If you do not end up with 0 then you have a mismatch.

You will find that the '(' in front of '28.065' is not matched.

Sargondjani on 21 Jun 2012

tip: if you go with your cursor over a bracket, you will see which bracket it is 'connected' with

Jan Simon on 21 Jun 2012

@Yagnaseni Roy: The error message "unexpected parenthesis" clearly hits the point. Walter's re-phrasing is more detailed.
@Walter: It is not trivial to decide, which of the parentheses is the unmatched one. It could be "(28.065*cos(60*t)+ 0.2094395101999999*x)" also. I'm convinced that you have used a smart pattern matching method trained by years of experiences with structured formulas. Nice, +1.

Answer by Siva Malla on 21 Jun 2012

this is correct:

(50*y)*(28.065*cos(60*t+0.2094395101999999*x))+22.7058*cos(2*(60*t+0.2094395101999999*x))+15.1368*cos(3*(60*t+0.2094395101999999*x))+7.014*cos(4*(60*t+0.2094395101999999*x));

## 1 Comment

Jan Simon on 21 Jun 2012

I agree that it is likely, that there is no COS inside the argument of a COS, but I would not dare to call this correct without asking the OP before.