Matlab Help

Trying to put the frequencies into an array:

fmax = input('Enter a maximum frequency: ', 's');
fint = input( 'Enter a frequency interval: ', 's');
freq = [0:fint:fmax]

But keeps coming up with error message:

??? Error using ==> colon
For colon operator with char operands, first and last operands must be char.

Any ideas?

Reply 1

iainthegreat

bump

Matlab Is Evil!!!

The freq bit maybe? I don't know what it's supposed to be.

Reply 4

Dizmo

freq = [0fmax]
Error: Unexpected MATLAB expression.

Well there's your problem. What are you trying to do?

Reply 5

jpye11

Man, I feel your pain with this stuff.

I've wasted so many hours trying to solve problems like this...

Reply 6

EvenStevens

Oh, actually I see now.

You want a new vector called freq which has the numbers between 0 and fmax?

It's because fmax is coming in as a string on input and what you're essentially saying is "Make a new array called freq and put in it the numbers between the number 0 and the word '5'", assuming you input 5 for your 'fmax' value.

You want to convert fmax to an integer before you start doing arithmetic with it.

Try...

fmaxtemp = input('Enter a maximum frequency: ', 's');
finttemp = input( 'Enter a frequency interval: ', 's');
fmax = str2num(fmaxtemp);
fint = str2num(finttemp);
freq = [0:fmax]

The str2num function will convert strings to numbers.

You could shorten it by going

fmax = str2num(input('Enter a maximum frequency: ', 's'));
fint= str2num(input( 'Enter a frequency interval: ', 's'));
freq = [0:fmax]

It does the same thing, but is just less easy to read.

Reply 7

Dizmo

Or just...

fmax = input('Enter a maximum frequency: ');
fint= input( 'Enter a frequency interval: ');
freq = [0:fmax]

The 's' converts tells Matlab to view it as a character string, so you're effectively converting it to characters then converting back.