MATLAB: Error using / Matrix dimensions must agree. (tried using .* and ./)

Question

Hi,

i am getting stuck with this error

Error using / Matrix dimensions must agree.

Error in Problem_2_3 (line 98)

s=(-1/(r*2*c))+sqrt((1/(2*r.*c)).^2-(1/(l*c)))

Here is my code

%%

%(b)

r=[100:100:1000] %ohms

c=1e-06; %farads

l=0.64; %henrys

s=(-1/(r*2*c))+sqrt((1/(2*r.*c)).^2-(1/(l*c)))

First_result= -s

Second_result= +s

Answer 1

You need to vectorise the division, using ./ instead of /.

This works:

r=[100:100:1000] %ohms
c=1e-06; %farads
l=0.64; %henrys
s=(-1./(r*2*c))+sqrt((1./(2*r.*c)).^2-(1/(l*c)))
First_result= -s
Second_result= +s

See the documentation on Array vs. Matrix Operations (link) for a relevant discussion.