How to plot a function using a variable that is calculated over a range?

Hello there,

I am new to plotting in MATLAB and am interested in plotting a function using a variable that is calculated over a range. I am getting an error that my matrix dimensions must agree. x is a matrix that is increasing from a to b with 2000 entries. I want to calculate a y that has the same number of entries as x and where x is used in the calculation. Once y is calculated I am interested in plotting y(x).

a = 1.7; 
b = 1.3;
c = 0.9; 
L = 2000; % Matrix size (1x2000)
l = 0 : (L-1); 
x = b + l*((a-b)/L); 

y = (c/(2*pi*(sqrt((a*a)-(x.^2))))*(2*atan(sqrt((x.^2)-(b*b))/sqrt((a*a)-(x.^2)))));

figure
plot(x,y,'Color',[0,0.7,0.9])
title('2-D Line Plot')
xlabel('x')
ylabel('y')

Answer 1

[Star Strider]

When in doubt, vectorise every multiplication, exponention, and division.

With those changes (and nothing else) it works —

a = 1.7; 
b = 1.3;
c = 0.9; 
L = 2000; % Matrix size (1x2000)
l = 0 : (L-1); 
x = b + l*((a-b)/L); 

y = (c./(2*pi*(sqrt((a*a)-(x.^2)))).*(2*atan(sqrt((x.^2)-(b*b))./sqrt((a*a)-(x.^2)))));

figure
plot(x,y,'Color',[0,0.7,0.9])
title('2-D Line Plot')
xlabel('x')
ylabel('y')

I vectorised everything not already vectorised except a*a and b*b, since they obviously do not need vectorisation.

.

[George]

Thats a great rule of thumb to vectorize every operation. Thank you very much for the help!

[Star Strider]

As always, my pleasure!