How can I add a few extra things in my Graph?

How can i get my matlab code to give me a graph with A B C and D as shown in the image. My code so far is also posted. I will also like to add a dashed line with the 6% offset. I do not know how to do these two things.

close all
clear all
clc

% The data show wer obatined from a tensile test of high=strenght stell.
% The test specimen had a diameter of 0.505 in and a gage lenth of 2.00
% in. elongation between the gage marks was 0.12 in and the minimum
% diameter was 0.42.

% Plot the conventional stress-strain curve for the steel and determine the
% propotional modulus of elasticity, yield stress at 0.1% offset, ultimate
% stress, percent elongation is 2.00 in., and percent reduction in area. 
% l = load in lbs e = elongation in inches d = diameter A = area S = Stress
% L = initial lenth E = strain in elongation p = percentage of elongation
% r = reduction in area k = elasticity
l = [1000 2000 6000 10000 12000 12900 13400 13600 13800 14000 14400 15200 16800 18400 20000 22400];
e = [.0002 .0006 .0019 .0033 .0039 .0043 .0047 .0054 .0063 .0090 .0102 .0130 .0230 .0336 .0507 .1108];
d = 0.505;
L = 2;
A = (pi*d^2)/4;
S = l/A;
E = e/L;
plot (E,S)
grid on
hold on
xlabel('Strain')
ylabel('Stress')
title('Stress-Strain Diagram')
hold off
%Propotional limit comes out to 65000 psi
%Yield stress = 68897.88 psi
%Ultimate stress = 112832.76 psi
k = 49926/1.65*10^-3 %Comes out in psi of the modulus of elasticity
p = (.12/2)*100 %comes out in percent of elongation of the speciemen
r = ((.2-.138)/.2)*100 %comes out in percent of area

Answer 1

[Simon Chan]

You may use function text to insert text on the figure.

You may define the text position better by assigning the position manually.

Edit for correction of the offset line:

Use 0.1% mentioned in the text inside your code instead of 6% which may not be practical. Anyway, you may adjust on the following code

plot(E,S);
grid on
hold on
xlabel('Strain')
ylabel('Stress')
title('Stress-Strain Diagram')
textname = {'A','B','C','D'};
pointA = 65000;
pointB = 68897.88;
pointC = 68897.88;
pointD = 112832.76;
pointAll = [pointA,pointB,pointC,pointD];
for k = 1:4
    xpos = E(S<pointAll(k));
    if k<3
        offset = -0.002;
    else
        offset = 0.002;
    end
    text(xpos(end)+offset,pointAll(k),textname{k},'FontSize',14,'FontAngle','italic');
end
%%  Proportional Region (Region yield stress at 0.1% offset)
%
%
idx.proportional = sum(S<pointA);                               % Index for proportional region
slope = (S(idx.proportional)-S(1))/(E(idx.proportional)-E(1));  % Calculate slope
new_E = E + 0.001;                                              % Adding offset for strain
new_S = slope*E;                                                % New stress for same slope
idx.plot = new_S<pointD;                                        % Limit the plot for stress below maximum stress
plot(new_E(idx.plot),new_S(idx.plot),'r--');                    % Plot the offset line
hold off