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angle

Phase angle

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Syntax

theta = angle(z)

Description

theta = angle(z) returns the phase angle in the interval [-π,π] for each element of a complex array z. The angles in theta are such that z = abs(z).*exp(i*theta).

example

Examples

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Open Live Script

Create a complex number, and compute its magnitude and phase.

z = 2*exp(i*0.5)
z = 
1.7552 + 0.9589i

r = abs(z)
r = 
2

theta = angle(z)
theta = 
0.5000
Open Live Script

Create a signal that consists of two sinusoids of frequencies 15 Hz and 40 Hz. The first sinusoid has a phase of -π/4, and the second has a phase of π/2. Sample the signal at 100 Hz for one second.

fs = 100;
t = 0:1/fs:1-1/fs;
x = cos(2*pi*15*t - pi/4) - sin(2*pi*40*t);

Compute the Fourier transform of the signal. Plot the magnitude of the transform as a function of frequency.

y = fft(x);
z = fftshift(y);

ly = length(y);
f = (-ly/2:ly/2-1)/ly*fs;

stem(f,abs(z))
xlabel 'Frequency (Hz)'
ylabel '|y|'
grid

Figure contains an axes object. The axes object with xlabel Frequency (Hz), ylabel |y| contains an object of type stem.

Compute the phase of the transform, removing small-magnitude transform values. Plot the phase as a function of frequency.

tol = 1e-6;
z(abs(z) < tol) = 0;

theta = angle(z);

stem(f,theta/pi)
xlabel 'Frequency (Hz)'
ylabel 'Phase / \pi'
grid

Figure contains an axes object. The axes object with xlabel Frequency (Hz), ylabel Phase / blank pi contains an object of type stem.

Input Arguments

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Input array, specified as a scalar, vector, matrix, or multidimensional array. When the elements of z are non-negative real numbers, angle returns 0. When the elements of z are negative real numbers, angle returns π.

Data Types: double | single
Complex Number Support: Yes

Algorithms

angle takes a complex number z = x + iy and uses the atan2 function to compute the angle between the positive x-axis and a ray from the origin to the point (x,y) in the xy-plane.

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using MATLAB® Coder™.

GPU Code Generation
Generate CUDA® code for NVIDIA® GPUs using GPU Coder™.

Version History

Introduced before R2006a

See Also

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