## unbalanced parenthesis on a problem

### Kylie Nedelka (view profile)

on 1 Feb 2018
Latest activity Edited by John D'Errico

### John D'Errico (view profile)

on 1 Feb 2018
trying to write this on matlab and keep gettting error in parenthesis

M

### M (view profile)

on 1 Feb 2018
The posted link seems to be broken.

on 1 Feb 2018
I don't know what that bar at the end is supposed to mean, but none of this is Matlab yet. What did you try?
Kylie Nedelka

### Kylie Nedelka (view profile)

on 1 Feb 2018
sorry, it is supposed to be 2cos(2pi((f(1)-f(2)/2)t)sin(2pi((f(1)+f(2)/2)t) and i cannot seem to type it correctly in matlab

### John D'Errico (view profile)

on 1 Feb 2018
Edited by John D'Errico

### John D'Errico (view profile)

on 1 Feb 2018

I would start by writing it using valid syntax for MATLAB. This is not that.
2cos(2pi((f(1)-f(2)/2)t)sin(2pi((f(1)+f(2)/2)t)
If you do not put a * between 2 and cos, then MATLAB will generate an error. The same applies for all of the other spots where you did not use * for multiplication. That it is common shorthand to not use a multiplication operator when you write, that does not apply to MATLAB. If you choose not to use *, you will get all sorts of errors, but not valid code.
MATLAB uses * for multiplication. Use it.
As far as the valid use os parens, I cannot even know for certain what you intended to write. There are (at least) two missing right parens in that expression.
sum('2cos(2pi((f(1)-f(2)/2)t)sin(2pi((f(1)+f(2)/2)t)' == '(')
ans =
10
sum('2cos(2pi((f(1)-f(2)/2)t)sin(2pi((f(1)+f(2)/2)t)' == ')')
ans =
8
Edit:
Now that you have actually attached a valid picture of what you want, write it in pieces. If you cannot figure out how to write an expression, just start in the inside.
f(1) - f(2)
Then divide by 2. Note that at each and every step, I'm making sure the parens matchup, because I added at most one left and one right parens at a time.
(f(1) - f(2))/2
Multiply by 2*pi.
2*pi*(f(1) - f(2))/2
and by t...
2*pi*(f(1) - f(2))/2*t
Here, make sure you understand that division and multiplication have the same order of precedence. So in MATLAB, we understand that 2/2*2 is 2, because MATLAB parses that as essentially (2/2)*2. Be careful, because many people make the mistake, thinking that 2/2*2==2/(2*2).That is not true.
Now take the cosine...
cos(2*pi*(f(1) - f(2))/2*t)
Do the same for the second half of the expression, which is identical, except for sin versus cos, and a plus in the middle. You should get this:
sin(2*pi*(f(1) + f(2))/2*t)
Combine the two sub-expressions, and multiply by 2
2*cos(2*pi*(f(1) - f(2))/2*t) * sin(2*pi*(f(1) + f(2))/2*t)
All I did was work outwards, in very simple steps.
If you can't solve a problem that is too large for you to handle, break it down into SMALL pieces, all of which are solvable. And learn to use MATLAB operators.

### Star Strider (view profile)

on 1 Feb 2018

‘sorry, it is supposed to be 2cos(2pi((f(1)-f(2)/2)t)sin(2pi((f(1)+f(2)/2)t)’
MATLAB does not recognise implied multiplication. You need to insert the appropriate operators.
Example
2*cos(2*pi*((f(1)-f(2)/2)*t)*sin(2*pi((f(1)+f(2)/2)*t)
Unless you intend to do array operations, use Vectorization (link) to do element-wise operations.
Also, what do ‘f(1)’ and ‘f(2)’ refer to? Is ‘f’ a function or a vector?