def test_hyper_as_trig():
from diofant.simplify.fu import _osborne as o, _osbornei as i, TR12
eq = sinh(x)**2 + cosh(x)**2
t, f = hyper_as_trig(eq)
assert f(fu(t)) == cosh(2*x)
e, f = hyper_as_trig(tanh(x + y))
assert f(TR12(e)) == (tanh(x) + tanh(y))/(tanh(x)*tanh(y) + 1)
d = Dummy()
assert o(sinh(x), d) == I*sin(x*d)
assert o(tanh(x), d) == I*tan(x*d)
assert o(coth(x), d) == cot(x*d)/I
assert o(cosh(x), d) == cos(x*d)
for func in (sinh, cosh, tanh, coth):
h = func(pi)
assert i(o(h, d), d) == h
# /!\ the _osborne functions are not meant to work
# in the o(i(trig, d), d) direction so we just check
# that they work as they are supposed to work
assert i(cos(x*y), y) == cosh(x)
assert i(sin(x*y), y) == sinh(x)/I
assert i(tan(x*y), y) == tanh(x)/I
assert i(cot(x*y), y) == coth(x)*I
assert i(sec(x*y), y) == 1/cosh(x)
assert i(csc(x*y), y) == I/sinh(x)
def test_hyper_as_trig():
eq = sinh(x)**2 + cosh(x)**2
t, f = hyper_as_trig(eq)
assert f(fu(t)) == cosh(2*x)
e, f = hyper_as_trig(tanh(x + y))
assert f(TR12(e)) == (tanh(x) + tanh(y))/(tanh(x)*tanh(y) + 1)
d = Dummy()
assert o(sinh(x), d) == I*sin(x*d)
assert o(tanh(x), d) == I*tan(x*d)
assert o(coth(x), d) == cot(x*d)/I
assert o(cosh(x), d) == cos(x*d)
for func in (sinh, cosh, tanh, coth):
h = func(pi)
assert i(o(h, d), d) == h
# /!\ the _osborne functions are not meant to work
# in the o(i(trig, d), d) direction so we just check
# that they work as they are supposed to work
assert i(cos(x*y), y) == cosh(x)
assert i(sin(x*y), y) == sinh(x)/I
assert i(tan(x*y), y) == tanh(x)/I
assert i(cot(x*y), y) == coth(x)*I
assert i(sec(x*y), y) == 1/cosh(x)
assert i(csc(x*y), y) == I/sinh(x)
def futrig(e, **kwargs):
"""Return simplified ``e`` using Fu-like transformations.
This is not the "Fu" algorithm. This is called by default
from ``trigsimp``. By default, hyperbolics subexpressions
will be simplified, but this can be disabled by setting
``hyper=False``.
Examples
========
>>> from diofant import trigsimp, tan, sinh, tanh
>>> from diofant.simplify.trigsimp import futrig
>>> from diofant.abc import x
>>> trigsimp(1/tan(x)**2)
tan(x)**(-2)
>>> futrig(sinh(x)/tanh(x))
cosh(x)
"""
from diofant.simplify.fu import hyper_as_trig
from diofant.simplify.simplify import bottom_up
e = sympify(e)
if not isinstance(e, Basic):
return e
if not e.args:
return e
old = e
e = bottom_up(e, lambda x: _futrig(x, **kwargs))
if kwargs.pop('hyper', True) and e.has(HyperbolicFunction):
e, f = hyper_as_trig(e)
e = f(_futrig(e))
if e != old and e.is_Mul and e.args[0].is_Rational:
# redistribute leading coeff on 2-arg Add
e = Mul(*e.as_coeff_Mul())
return e
def exptrigsimp(expr, simplify=True):
"""
Simplifies exponential / trigonometric / hyperbolic functions.
When ``simplify`` is True (default) the expression obtained after the
simplification step will be then be passed through simplify to
precondition it so the final transformations will be applied.
Examples
========
>>> from diofant import exptrigsimp, exp, cosh, sinh
>>> from diofant.abc import z
>>> exptrigsimp(exp(z) + exp(-z))
2*cosh(z)
>>> exptrigsimp(cosh(z) - sinh(z))
E**(-z)
"""
from diofant.simplify.fu import hyper_as_trig, TR2i
from diofant.simplify.simplify import bottom_up
def exp_trig(e):
# select the better of e, and e rewritten in terms of exp or trig
# functions
choices = [e]
if e.has(*_trigs):
choices.append(e.rewrite(exp))
choices.append(e.rewrite(cos))
return min(*choices, key=count_ops)
newexpr = bottom_up(expr, exp_trig)
if simplify:
newexpr = newexpr.simplify()
# conversion from exp to hyperbolic
ex = {a
for a in newexpr.atoms(Pow)
if a.base is S.Exp1} | newexpr.atoms(S.Exp1)
if ex:
ex0 = {list(ex)[0]}
ex = [ei for ei in ex if 1 / ei not in ex]
if not ex:
ex = ex0
# sinh and cosh
for ei in ex:
a = ei.exp if ei is not S.Exp1 else S.One
newexpr = newexpr.subs(ei + 1 / ei, 2 * cosh(a))
newexpr = newexpr.subs(ei - 1 / ei, 2 * sinh(a))
e2 = ei**-2
if e2 in ex:
a = e2.exp / 2 if e2 is not S.Exp1 else S.Half
newexpr = newexpr.subs((e2 + 1) * ei, 2 * cosh(a))
newexpr = newexpr.subs((e2 - 1) * ei, 2 * sinh(a))
# exp ratios to tan and tanh
for ei in ex:
n, d = ei - 1, ei + 1
et = n / d
etinv = d / n # not 1/et or else recursion errors arise
a = ei.exp if ei.is_Pow and ei.base is S.Exp1 else S.One
if a.is_Mul or a is S.ImaginaryUnit:
c = a.as_coefficient(I)
if c:
t = S.ImaginaryUnit * tan(c / 2)
newexpr = newexpr.subs(etinv, 1 / t)
newexpr = newexpr.subs(et, t)
continue
t = tanh(a / 2)
newexpr = newexpr.subs(etinv, 1 / t)
newexpr = newexpr.subs(et, t)
# sin/cos and sinh/cosh ratios to tan and tanh, respectively
if newexpr.has(HyperbolicFunction):
e, f = hyper_as_trig(newexpr)
newexpr = f(TR2i(e))
if newexpr.has(TrigonometricFunction):
newexpr = TR2i(newexpr)
# can we ever generate an I where there was none previously?
if not (newexpr.has(I) and not expr.has(I)):
expr = newexpr
return expr