MATLAB: Is there a function that returns the real root from a matrix that contains the roots of a function

function

i want to return the real root from a vector contains the roots of a function, this vector contains both imaginary and real roots

Best Answer

If R is the vector of roots, then

R(imag(R) == 0)

Related Solutions

MATLAB: How to threshold only real part of a complex matrix

>> A = complex(randi([-3,3],4,4),randi([-3,3],4,4)) % fake data
A =
  -2 + 3i  -2 + 1i   2 - 3i  -2 + 1i
  -2 + 0i   3 + 0i  -3 + 3i   0 + 0i
   2 + 0i   2 - 2i   3 + 3i   0 - 3i
   1 - 2i  -3 - 2i   3 + 2i   0 - 2i
>> B = complex(real(A).*(real(A)<=0.5),imag(A)) % set real(A)>0.5 to 0.
B =
  -2 + 3i  -2 + 1i   0 - 3i  -2 + 1i
  -2 + 0i   0 + 0i  -3 + 3i   0 + 0i
   0 + 0i   0 - 2i   0 + 3i   0 - 3i
   0 - 2i  -3 - 2i   0 + 2i   0 - 2i

MATLAB: How to use integral2 when the integrand is a array

http://www.mathworks.com/help/matlab/math/parameterizing-functions.html

d=1e-9:1e-10:3e-9;
output = arrayfun(@(D) integral2(@(x,y) Tuu(x, y, D), 0,pi/2,0,pi/4,'reltol', 2e-4), d);
function U=Tuu(x, y, d)
mu=8;
delta=10;
vh=16;
HBAR=1.05457266e-34;
ME=9.1093897e-31;
ELEC=1.60217733e-19;
Kh=2.116e10;
kc=sqrt(2.*ME.*ELEC./HBAR.^2);
ku=kc.*sqrt(mu+delta);
kd=kc.*sqrt(mu-delta);
puu1=sqrt(ku.^2-ku.^2.*sin(x).^2+kc.^2.*vh);
puu2=sqrt(ku.^2-ku.^2.*sin(x).^2-kc.^2.*vh);
quu1=sqrt(ku.^2-(Kh-ku.*sin(x).*cos(y)).^2-ku.^2.*sin(x).^2.*sin(y).^2+kc.^2.*vh);
quu2=sqrt(ku.^2-(Kh-ku.*sin(x).*cos(y)).^2-ku.^2.*sin(x).^2.*sin(y).^2-kc.^2.*vh);
U=1/4.*ku.*sin(x).*(real(puu1).*exp(-2.*imag(puu1).*d)+real(puu2).*exp(-2.*imag(puu2).*d)+real(quu1).*exp(-2.*imag(quu1).*d)+real(quu2).*exp(-2.*imag(quu2).*d)+((real(puu1)+real(puu2)).*cos((real(puu1)-real(puu2)).*d)-(imag(puu1)-imag(puu2)).*sin((real(puu1)-real(puu2)).*d)).*exp(-(imag(puu1)+imag(puu2)).*d)-((real(quu1)+real(quu2)).*cos((real(quu1)-real(quu2)).*d)-(real(quu1)-imag(quu2)).*sin((real(quu1)-real(quu2)).*d)).*exp(-(imag(quu1)+imag(quu2)).*d));
end

If you try to use a smaller relative tolerance then you will get warning messages about using too many iterations. Your integrals are in the range of 2E20 so they do not converge well.

Best Answer

Related Solutions

MATLAB: How to threshold only real part of a complex matrix

MATLAB: How to use integral2 when the integrand is a array

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