i am trying to add a legend for the 0.2% offset line onto the graph, but when i run this, the previous three legend just disappear.

%plot with errorbar

plot(strain,stress)

hold on

title('strain vs. stress')

xlabel('strain (in/in)')

ylabel('stress (psi)')

errorbar(strain(1:200:end),stress(1:200:end),u_stress(1:200:end),'.','vertical')

errorbar(strain(1:200:end),stress(1:200:end),u_strain(1:200:end),'.','horizontal')

legend('calculated stress and strain','uncertainty in stress','uncertainty in strain')

%plot offset line

x1 = 0.000363009;

x2 = 0.000469177;

y1 = 15511.2;

y2 = 18918.3;

E = (y2-y1)/(x2-x1);%calculate the young's modulus

x_off = 0.002:0.0001:0.0032;

y_off = E*(x_off-0.002);

hold on

plot(x_off,y_off);

legend('0.2 offset line')

Answer 1

[Alan Stevens]

Just put '0.2 offset line' as a fourth item in your other legend command.