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unwind(angleMat [, crit:Val]) where angleMat is REAL matrix and
  .5 <= Val < 1

Keywords: time series, complex arithmetic
unwind(angleMat) attempts to eliminate or reduce discontinuities (jumps
between rows) in each column of matrix angleMat, considered as being a
sequence of angles.

The assumed units of the angles are as specified by option 'angles'
("radians", "degrees", or "cycles").  For example, if angles are
measured in degrees, unwind(vector(350, 352, 359, 2, 1, 355)) is
vector(350, 352, 359, 362, 361, 355).  See subtopic 'options:"angles"'.

The operation of unwind() is controlled by the value Val of a criterion.
Let Jump = abs(angleMat[i,j] - angleMat[i-1,j]).  Then when Jump >
Val*Cycle, where Cycle is 2*pi radians, 360 degrees or 1 cycle,
angleMat[i,j] is increased or decreased by a multiple of Cycle so as to
bring the change less than Val*Cycle .  The default is Val = 0.75.

unwind(angleMat,crit:Val) uses Val for the unwinding criterion.  Val
must be between 0.5 and 1 cycles even when option 'angles' has value
"radians" or "degrees".

See also topics hpolar(), cpolar(), subtopic 'options:"angles"'.

Gary Oehlert 2003-01-15