unwrapMultipart

Create a vector of phase angles from 0 to 4$\pi$ that is separated into two parts by a NaN value. Use the phase angles to define the $\mathit{xy}$-coordinates of a spiral.

t1 = linspace(0,1.75*pi);
t2 = linspace(2.25*pi,4*pi);
t = [t1 NaN t2];

x = t/pi.*cos(t);
y = t/pi.*sin(t);
plot(x,y)

Find the phase angle of the spiral from the $\mathit{xy}$-coordinates by using the atan2 function. The atan2 function returns the angle values within the closed interval from $-\pi$ to $\pi$.

P = atan2(y,x);
plot(t,P)

Note that the plot has discontinuities. Eliminate the discontinuities by using the unwrapMultipart function. The unwrapMultipart function independently unwraps the NaN-separated parts of the vector.

Q1 = unwrapMultipart(P);
plot(t,Q1)

Compare the result with the unwrap function, which does not independently unwrap NaN-separated parts.

Q2 = unwrap(P);
plot(t,Q2)

Create a vector of longitudes from 0 to 720 degrees that is separated into two parts by a NaN value.

lon = [0:20:340 NaN 380:20:720];

Wrap the longitudes to the closed interval from –180 to 180 degrees by using the wrapTo180 function.

P = wrapTo180(lon);
plot(P)

Unwrap the longitude angles by using the unwrapMultipart function. The function independently unwraps the NaN-separated parts of the vector.

Q = unwrapMultipart(P,"degrees");
plot(Q)

Compare the result to the unwrap function, which works only in radians and does not independently unwrap NaN-separated parts.

rad = deg2rad(P);
Q2 = unwrap(rad);
plot(Q2)