MATLAB Function Reference

unwrap

Correct phase angles

Syntax

Q = unwrap(P)
Q = unwrap(P,tol)
Q = unwrap(P,[],dim)
Q = unwrap(P,tol,dim)

Description

Q = unwrap(P) corrects the radian phase angles in array P by adding multiples of ±2 when absolute jumps between consecutive array elements are greater than radians. If P is a matrix, unwrap operates columnwise. If P is a multidimensional array, unwrap operates on the first nonsingleton dimension.

Q = unwrap(P,tol) uses a jump tolerance tol instead of the default value, .

Q = unwrap(P,[],dim) unwraps along dim using the default tolerance.

Q = unwrap(P,tol,dim) uses a jump tolerance of tol.

Examples

Array P features smoothly increasing phase angles except for discontinuities at elements (3,1) and (1,2).

P =
         0    7.0686    1.5708    2.3562
    0.1963    0.9817    1.7671    2.5525
    6.6759    1.1781    1.9635    2.7489
    0.5890    1.3744    2.1598    2.9452

The function Q = unwrap(P) eliminates these discontinuities.

Q =
         0    0.7854    1.5708    2.3562
    0.1963    0.9817    1.7671    2.5525
    0.3927    1.1781    1.9635    2.7489
    0.5890    1.3744    2.1598    2.9452

Limitations

The unwrap function detects branch cut crossings, but it can be fooled by sparse, rapidly changing phase values.

See Also

abs, angle

unix

upper