I having trouble with functions

I'm having trouble with my function working with an electrical field problem:

I have my code inserted below, but don't seem to understand how to do the second half of the problem by. Any help would be great. Thank You.

Main Code:

Q = linspace(1,12,12); %sec

r = linspace(0.05,0.6,12); %meter

Q = linspace(1,14,14); %sec

r = linspace(0.76,0.89,14); %meter

Q_t1 = linspace(1.3,1.5,12);

Q_t2 = linspace(1.3,1.7,14); %This is for the second half

[E] = E_sphere(r, Q);

%[E] = E_sphere(r, Q); %This is for the second half

subplot(1,2,1)

plot(E,Q_t1)

subplot(1,2,2)

plot(E,Q_t2)

Function Code:

function [E] = E_sphere(r,Q)

      e_o = 8.85e-12; %F/m

      E = (Q)/4.*pi.*e_o.*r.*(Q).^2;
  end

Answer 1

[Geoff Hayes]

Jim - it isn't clear why you are overwriting your r and Q for the first half with that from the second half. Try keeping your local variables distinct as

 Q1 = linspace(1.3,1.5,12); %sec
 r1 = linspace(0.05,0.6,12); %meter
 Q2 = linspace(1.3,1.7,14); %sec
 r2 = linspace(0.76,0.89,14); %meter

Then call your function twice as

 E1 = E_sphere(r1,Q1);
 E2 = E_sphere(r2,Q2);

The inputs to your function do not have to be named r and Q. Likewise, the output does not have to be named E. They can be named however you want but you do want the names to be relevant or specific to their purpose. In this case, I have just added a 1 or 2 to the end of each to indicate that the inputs and results are from data set 1 or 2.

Also, note how the Q's are initialized as per the problem description.