Question about plotting/vectors

Hey guys, sorry for asking probably completely noob question here, but I actually need help asap. So I'm supposed to do some basic graphs about strains, and I have my formulae which I wrote in the matlab. My sigmax strain for y=0 and for x=-5 (or 5, it's actually radius of a circle) should be 0, and my function gives that result. Since I wanted to plot of it, I just put x=-5:0.01:5 but then my results are completely different. I'm pretty sure I'm just an idiot but I'm still a complete newbie at this program. Anyway here's the code:

if true
  R=5;
F=100;
x=-5 %the part I'm having problem with, if I put x=-5:0.01:5, my sigmax doesn't go from 0 to 0
y=0
K=(x.^2+(R-y)^2).^2.*(x.^2+(R+y)^2).^2;
C=x.^4+(R^2-y^2)*(R^2+3*y^2+2.*x.^2);
sigmax=(F/(pi*R))-((4*F*R.*x.^2)/(pi.*K))*C
end

Answer 1

[Thorsten]

When x is a vector you have to use element-wise multiplication and division

 sigmax=(F/(pi*R))-((4*F*R.*x.^2)./(pi.*K)).*C

[Ivan]

Ugh I feel even worse now, I'm actually blind af. Thank you for the help :)

Answer 2

[Birdman]

    R=5;
    F=100; 
    x=-5:0.01:5; %the part I'm having problem with, if I put x=-5:0.01:5, my sigmax doesn't go from 0 to 0
    y=0;
    K=(x.^2+(R-y)^2).^2.*(x.^2+(R+y)^2).^2;
    C=x.^4+(R^2-y^2)*(R^2+3*y^2+2.*x.^2);
    sigmax=(F./(pi.*R))-((4*F*R.*x.^2)./(pi.*K)).*C;
    plot(x,sigmax)

[Ivan]

Thank you for the help, I guess I'm just blind.