1> function cerchio(c,r)
> t = linspace(0, 2*pi);
> z = r * exp(i*t) + c;
> plot(real(z),imag(z));
> axis equal;
> end


2> cerchio(1+3*i,2)


3> cerchio(1+3*i,2)


4> grid on


5> function gersh(A)
> for k = 1:length(A)
> c(k) = abs(A(k,k));
> r(k) = sum(abs(A(k,:))) - c(k);
> cerchio(c(k),r(k));
> hold on;
> end
> [x,la] = eig(A);
> lambda = diag(la);
> for k = 1:length(A)
> plot(real(lambda(k)),imag(lambda(k)),'*');
> end;
> end


6> edit


7> help gersh
error: help: `gersh' is not documented


7> edit gersh


8> help gersh
error: help: `gersh' is not documented


8> clear gersh


9> help gersh
error: help: `gersh' is not documented


9> reloadpath
error: `reloadpath' undefined near line 9 column 1


9> reloadpath()
error: `reloadpath' undefined near line 9 column 1


9> quit



1> edit cerchio


2> cerchio(1+3*i,2)


3> help gersh
`gersh' is a function from the file C:\Documents and Settings\rudiger.achilles\desktop\gersh.m

 plot dei cerchi di Gershgorin della matrice A

Additional help for built-in functions and operators is
available in the on-line version of the manual.  Use the command
`doc <topic>' to search the manual index.

Help and information about Octave is also available on the WWW
at http://www.octave.org and via the help@octave.org
mailing list.


4> A = [1+3i 2-4i 5; 4-i 7-i 6; 3 2+i 3+i]
A =

   1 + 3i   2 - 4i   5 + 0i
   4 - 1i   7 - 1i   6 + 0i
   3 + 0i   2 + 1i   3 + 1i



5> gersh(A)


6> quit