Code for an equation

I want to plot y = (3.5^(-.5x))*cos(6x) for x= -2 to x= 4 with interval of 0.01 without using for loop.

Following is the code I am writing:

clc
x = [-2:.01:4];
y = (3.5.^(-.5*x))*(cos(6*x));
plot(x,y);

But I recieve this error

Error using  * 
Inner matrix dimensions must agree.

Answer 1

[Aviel Moos]

You need to use elementwise multimplication.

let look at this:

A = (3.5.^(-.5*x)); % Here you will get a vector with 601 elements
B = (cos(6*x)); % Here you will get also a vector with 601 elements

You cannot just multiply, You need to multiplay each element in place K of A with element in place K of B.

So just replace:

y = (3.5.^(-.5*x))*(cos(6*x));

with this:

y = (3.5.^(-.5*x)).*(cos(6*x));

[Malik Sheraz Nazam]

Thank you :D

Answer 2

[Adam Danz]

y = (3.5.^(-.5*x)).*(cos(6*x));
%                 ^ dot

[Malik Sheraz Nazam]

Thank you :D

[Adam Danz]

There must be huge delays in server synchronization. There was 6 min between the first and second answer and one more minute for the 3rd. I certainly didn't see any answers prior to the quick 1-liner I posted. I wonder if madhan ravi saw any.

[madhan ravi]

As I noticed in the activity feed the answer you & I gave were at the same time, but yours were a millisecond quicker so yours came up first. The 6 mins was delta between mine and the accepted if it's what you mean.

[Adam Danz]

The time stamps on the recent activity feed shows 15:14 (Moos' answer), 15:09 (for our ans'). I'm not sure how you're measuring milliseconds. Accepted answer at 15:16. In any case, I certainly did not see an answer despite the ~7min following the first answer.

[madhan ravi]

We are saying the same point in fact :)

[Malik Sheraz Nazam]

I wish I had option to accept all the answer.

You both made life easier for me.

Thanks :D

[Adam Danz]

I'm just here and help out and learn a lot in the process. Accepted answers and votes are quantitative measures of skill but your appreciation is the qualitative feedback that has a longer lasting positive effect.

Answer 3

[madhan ravi]

.*

[Malik Sheraz Nazam]

Thanks :D