number—a number.
phase—a number.
phase
returns the phase
of number (the angle part of its polar representation)
in radians, in the range
-π (exclusive) if minus zero is not supported, or
-π (inclusive) if minus zero is supported,
to π (inclusive). The phase of a positive
real
number
is zero; that of a negative
real
number is π.
The phase of zero is defined to be zero.
If number is a complex float, the result is a float of the same type as the components of number. If number is a float, the result is a float of the same type. If number is a rational or a complex rational, the result is a single float.
The branch cut for phase
lies along the negative real
axis, continuous with quadrant II. The range consists of that portion of
the real axis between -π (exclusive) and π (inclusive).
The mathematical definition of phase
is as follows:
(phase
x) = (atan (imagpart
x) (realpart
x))
(phase 1) → 0.0s0 (phase 0) → 0.0s0 (phase (cis 30)) → -1.4159266 (phase #c(0 1)) → 1.5707964
Should signal type-error
if its argument is not a number.
Might signal arithmetic-error
.