MATLAB Answers

What am I doing wrong here? I am trying to recreate following highlighted equations in the table.

1 view (last 30 days)
ep = linspace(0,1);
m1 = 1.5; m2 = 3.8;
ep0= 1; alpha = 0.785; epp = 0.11;
qep = (2.76*ep*cosh((3*ep)-1.92));
I1 = ep.^ m1;
I2 = ep.^ m2;
I3 = ep*((ep-epp)/(ep0-epp)).^alpha;
I6 = 1-(qep*((3*(1-ep))/(3-ep)));
Hold on
plot(ep,I1)
plot(ep,I2)
plot(ep,I3)
plot(ep,I6)
Hold off

Accepted Answer

Paul Hoffrichter
Paul Hoffrichter on 27 Mar 2021
Edited: Paul Hoffrichter on 27 Mar 2021
clc; clear; clf
ep = linspace(0,1);
m1 = 1.5; m2 = 3.8;
ep0= 1; alpha = 0.785; epp = 0.11;
qep = (2.76*ep.*cosh((3*ep)-1.92));
I1 = ep.^ m1;
I2 = ep.^ m2;
zz = (ep-epp)/(ep0-epp);
zza = zz .^ alpha; % zza is complex
I3 = ep .* zza;
I6 = 1-(qep*((3*(1-ep))/(3-ep)));
hold on
plot(ep,I1);
plot(ep,I2)
plot(ep,I3) % This is Line 18 - usually do not plot a complex vector like this
plot(ep,I6)
hold off
warning:
Warning: Imaginary parts of complex X and/or Y arguments ignored.
> In Untitled (line 18)
  4 Comments
Paul Hoffrichter
Paul Hoffrichter on 28 Mar 2021
I was a surprised at first about the complex numbers. But then I thought about what if alpha was 0.5 instead of 0.785. Then if x is a negative number, we have a purely imaginary result for x^(.5)=sqrt(x)= sqrt{(-1) * abs(x)} = 0 + j*sqrt(abs(x)). For other values of alpha between (0.5, 1.0), we get complex numbers.

Sign in to comment.

More Answers (0)

Products


Release

R2020b

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!