Dharmesh, since cosd(beta) with beta=25 is close to one, what you essentially are plotting is the inverse tangent of the tangent. The jump you see at 90 degrees is because the tangent becomes large and positive as theta approaches 90. The inverse tangent of that very large positive number (Inf) is 90. As soon as the angle goes past 90, call it 90+dtheta, the numerator in tangent is still a large positive number, but the denominator is a small negative number. That is the reason for the jump to -90. Over any interval where the "inverse" tangent actually behaves like a true inverse, you should get a line because phi1 is a line.
What makes you think the function should look smoother? Wayne
