Warning: Imaginary parts of complex X and/or Y arguments ignored

Hi Everybody,

I want to plot gp vs. q in the following code:

kab=3;

kba=3;

gp=0.0:0.0001:1.25;

gn=0.0:0.0001:1.25;

DeltaB=8.296;

H=((i*gp./2)-(i*gn./2))./((DeltaB./2)-i*gn./2);

q=sqrt(((DeltaB./2).^2-kab*kba-(DeltaB./2).*(i*gp./2+i*gn./2)-gp.*gn./4)./(1-H.*1));

T=10*log10((abs(q.*1)).^2./(abs((q.*cosh(-q.*i))+((DeltaB./2-i*gn./2).*sinh(-q.*i)))).^2.);

plot(gp,q,'r')

grid on

q has real and imaginary part, but I got only the real part, and the code said:

Warning: Imaginary parts of complex X and/or Y arguments ignored

Any help please

[Walter Roberson]

Please re-tag this question. See http://www.mathworks.co.uk/matlabcentral/answers/43073-a-guide-to-tags

[Jan]

Beside using meaningful tags (all questions concern Matlab here!), formatting your code would be helpful also: Answers: how-to-format-your-question-with-markup

Answer 1

[Wayne King]

What do you think you only have the real part?

   kab=3;
   kba=3;
   gp=0.0:0.0001:1.25;
   gn=0.0:0.0001:1.25;
   DeltaB=8.296;
   H=((i*gp./2)-(i*gn./2))./((DeltaB./2)-i*gn./2);
   q=sqrt(((DeltaB./2).^2-kab*kba-(DeltaB./2).*(i*gp./2+i*gn./2)-gp.*gn./4)./(1-H.*1));
  T=10*log10((abs(q.*1)).^2./(abs((q.*cosh(-q.*i))+((DeltaB./2-i*gn./2).*sinh(-q.*i)))).^2.);
  plot(gp,real(q),'r')

You are using the unit imaginary, i, in both H and both q.

Answer 2

[Walter Roberson]

Please re-tag this question. See http://www.mathworks.co.uk/matlabcentral/answers/43073-a-guide-to-tags