Define variable based on input condition

I have a function which calculates two possible output values (psi positive or negative) for a given input value (th2) as th2 sweeps from 0 to 360.

th2 = 0: 0.1: 360;

A = 2*a*c.*cosd(th2)-2*d*c;

B = 2*a*c.*sind(th2);

C = (d^2) + (c^2) + (a^2) - (b^2) - (2*a*d.*cosd(th2)) ;

psi_pos = (atan2d(B,A) + acosd(C ./ (sqrt((A.^2) + (B.^2)))));

psi_neg = (atan2d(B,A) - acosd(C ./ (sqrt((A.^2) + (B.^2)))));

The outputs for psi_pos and psi_neg are 1x3601 doubles,

I want a final variable psi defined as

psi_pos when 0 < th2 < 180

psi_neg when 180 < th2 < 360

So I can then plot one continuous function (psi vs th2)

Answer 1

[madhan ravi]

psi = ((0 <= th2) & (th2 < 180)) .* psi_pos + ((180 <= th2) & (th2 < 360)) .* psi_neg;
plot(th2, psi)