how to use the mathmatical constant "e" in conjunction with a vector.

I am trying to use the mathmatical constant "e" in conjunction with a vector and each time i rum my script i tells me that the " * " is wrong. I have narrowed it down by removign things one piece at a time and everything runs great until i add the e back into my script. i saw somewhere that you can use exp() to make it work but in conjunction with the rest of the function i am not getiing it to work.

[SonOfAFather]

i really don't like assigning e = exp(1) but if that works thats's fine. I would like to get this function done in a oneliner. here is what i have so far.

clear;

clc;

close all;

% create vector of time values

t = 0.0 : 0.01 : 5.0;

% evaluate function at time points

e = exp(1);

f = 22*cos(15*pi*t)*e.^(-0.5*t);

% plot t vs f(t)

figure(1)

plot(t,f);

xlabel('t (sec)');

ylabel('f(t)');

Error using *

Inner matrix dimensions must agree.

Error in tesst (line 8)

f = 22*cos(15*pi*t)*e.^(-0.5*t);

Answer 1

[Matt Tearle]

Your problem isn't the e, it's that the two parts you're trying to multiply are both vectors, hence you need .* instead of *:

f = 22*cos(15*pi*t) .* e.^(-0.5*t);
%      ---vector---    ---vector--

But, as Wayne King says, don't use e.^x, use exp(x):

f = 22*cos(15*pi*t) .* exp(-0.5*t);

[SonOfAFather]

thank you thank you i was pulling my hair out over this

Answer 2

[Wayne King]

You need to post some code so we can see where you encounter an error. You can certainly use exp() with vectors.

   x = 1:0.001:10;
   y = exp(x);
   % or
   z = exp(1)*ones(100,1);

Of course, you can always define a variable.

e = exp(1);

but I don't think you should need to do that.

Also, don't forget the "dot" notation if that is necessary.

 x = 1:0.001:10;
 y = exp(-x.^2);
 plot(x,y)

[SonOfAFather]

thank you thank you i was pulling my hair out over this