def sinh(x, err=defaultError):
"""
sinh(x [,err]) returns the hyperbolic sine of x.
"""
if not isinstance(err, defaultError.__class__) or err <= defaultError:
series = ExponentialPowerSeries(
itertools.cycle((
0,
rational.Integer(1),
)))
rx = rational.Rational(x)
if rx == 0:
return rational.Rational(0)
return series(rx, err)
else:
return rational.Rational(math.sinh(x))
