I want to save all the values of e1 and e2 and then I want to plot them

%clc
%close all
%clear

%Steel
n = 0.22;
r = 0.9;
for a = -1:1;
  nr1 = (1+r*(1-a))*(1-(2*r*a/1+r)+a^2);
  nr2 = ((1+r)*a-r)*(1-(2*r*a/1+r)+a^2);
  dr  = (1+r)*(1+a)*(1-((1+4*r+2*r^2)*a/(1+r)^2)+a^2);
  e1 = (nr1/dr)*n;
  e2 = (nr2/dr)*n;
end;
plot(e2,e1);

[dpb]

NB:

a=-1:1;

will return only three points, -1, 0, 1 which won't make much of a smooth plot for anything but a straight line.

NB2:

S Strider's solution via linspace will introduce 100 points between the bounds, enough to show the shape.

NB3:

in

nr1 = (1+r*(1-a))*(1-(2*r*a/1+r)+a^2);

the term (2*r*a/1+r) is same as 2*r*a+r, check for missing parentheses around the 1+r term that I'm guessing is supposed to be the divisor...

Answer 1

[Star Strider]

There are several ways to approach this.

This causes the least disruption to the code you posted:

n = 0.22;
r = 0.9;
av = linspace(-1, 1);
for k = 1:numel(av)
    a = av(k);
    nr1 = (1+r*(1-a))*(1-(2*r*a/1+r)+a^2);
    nr2 = ((1+r)*a-r)*(1-(2*r*a/1+r)+a^2);
    dr  = (1+r)*(1+a)*(1-((1+4*r+2*r^2)*a/(1+r)^2)+a^2);
    e1(k) = (nr1/dr)*n;
    e2(k) = (nr2/dr)*n;
end

figure
plot(e2,e1)
grid

Experiment to get the result you want.