How Can I Write This Function In Matlab? I Got Matrix Eror

Question

3.00/5 (1 vote)

See more:

How can i write this function in matlab? i got matrix eror

n=1:100; 
k=0.5; 
x[n]=sin((3*pi*n)/20); 
y(n)=x(n./k);
scale (x,k);

Posted 29-Dec-13 8:39am

Member 10493429

Updated 29-Dec-13 11:07am

Albert Holguin

v2

Add a Solution

Comments

Er. Tushar Srivastava 29-Dec-13 14:47pm

I guess you need to loop while using n in x(n) and y(n)

Member 10493429 29-Dec-13 14:57pm

i defined in this way
>> n=1:100;
>> k=0.5;
>> x(n)=sin((3*pi*n)/20);
>> y(n)=x(n/k);
Index exceeds matrix dimensions.

Er. Tushar Srivastava 29-Dec-13 15:05pm

that is obvious. Matrix Index start from 1 and if you will divide 1 by 0.5 = 0.5. That's why Matrix Index exceeds. Are you are trying to do x(n)/k ?

Member 10493429 29-Dec-13 15:18pm

no iwant to do x(n/k), itried to devide 0.5 to 0.5. but still have matrix eror .

Er. Tushar Srivastava 29-Dec-13 15:25pm

I said that already. index of a vector in MatLab starts with 1 i.e. x(1), x(2), x(3) ... so on. So you cannot have x(0) or x(0.5) etc. This is the reason of your error. when you do x(n/k), the first value of n = 1 so, it becomes x(1/0.5) = x(0.5) which exceeds the range i.e x(n) where n is a natural number excluding 0 i.e. from 1 to infinity. I hope it explained the error :)

Nelek 29-Dec-13 16:48pm

You explained it well, other point is if he understood it. My virtual 5

Er. Tushar Srivastava 29-Dec-13 16:52pm

Thank You :) and A Very Happy New Year to you :) I hope he will understand it :)

Albert Holguin 29-Dec-13 17:18pm

Not exactly... see my solution. You CAN loop, but the main problem is the use of n as an index.

1 solution

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Albert Holguin · Answer 1 · 2013-12-29T11:16:00

Solution 1

C#

1  n=1:100;
2  k=0.5;
3  x[n]=sin((3*pi*n)/20);
4  y(n)=x(n./k);
5  scale (x,k);

I put line numbers for reference...
Line one is fine, creates a vector from 1 to 100.
Line two defines a scalar value k.
Line three, this is invalid, you can't use a vector as an index. You can either loop or simply remove the index reference.

x=sin((3*pi*n)/20); %valid

Line four, same thing... invalid because you're using a vector as an index. You also don't need the ./ operator when one is a vector and the other is a scalar, it doesn't make sense. Also, this n/k will give you non-integer values for some values of n, which is not a valid index.

Posted 29-Dec-13 11:16am

Albert Holguin

Updated 30-Dec-13 12:30pm

v3

Comments

Er. Tushar Srivastava 29-Dec-13 17:44pm

Actually if line 3 is written as x(n) instead of x[n], the result will be a vector. Considering line 3 in question as x[n] being a typo error and assuming it as x(n). It is also valid. The main problem is with line 4 i.e. y(n) = x(n./k) or x(n/k); Here, n/k will result in a non integer and so the error (that's what you said is correct).

Albert Holguin 29-Dec-13 18:09pm

If you write it as I did the result is also a vector. Matlab can determine that on its own.

Er. Tushar Srivastava 29-Dec-13 18:14pm

I wrote line 3 as you have written and it throw an error (Unbalanced Something....)

Er. Tushar Srivastava 29-Dec-13 18:16pm

Ok I got it, sorry I didn't look at the next corrected step. My eyes scrolled too fast off the codes :-P

Albert Holguin 29-Dec-13 18:24pm

I work with Matlab every day... :)

Er. Tushar Srivastava 29-Dec-13 18:40pm

:) really sorry for I didn't see the correction you had made

Albert Holguin 30-Dec-13 18:33pm

I was wrong about the [] versus ()... guess I didn't remember that part right. Corrected that part.