def jacobi_elliptic_cn(u, m, verbose=False):
"""
Implements the jacobi elliptic cn function, using the expansion in
terms of q, from Abramowitz 16.23.2.
"""
u = convert_lossless(u)
m = convert_lossless(m)
if verbose:
print >> sys.stderr, '\nelliptic.jacobi_elliptic_cn'
print >> sys.stderr, '\tu: %1.12f' % u
print >> sys.stderr, '\tm: %1.12f' % m
zero = mpf('0')
onehalf = mpf('0.5')
one = mpf('1')
two = mpf('2')
if m == zero: # cn collapses to cos(u)
if verbose:
print >> sys.stderr, 'cn: special case, m == 0'
return cos(u)
elif m == one: # cn collapses to sech(u)
if verbose:
print >> sys.stderr, 'cn: special case, m == 1'
return sech(u)
else:
k = sqrt(m) # convert m to k
q = calculate_nome(k)
kprimesquared = one - k**2
kprime = sqrt(kprimesquared)
v = (pi * u) / (two * ellipk(k**2))
sum = zero
term = zero # series starts at zero
if verbose:
print >> sys.stderr, 'elliptic.jacobi_elliptic_cn: calculating'
while True:
factor1 = (q**(term + onehalf)) / (one + q**(two * term + one))
factor2 = cos((two * term + one) * v)
term_n = factor1 * factor2
sum = sum + term_n
if verbose:
print >> sys.stderr, '\tTerm: %d' % term,
print >> sys.stderr, '\tterm_n: %e' % term_n,
print >> sys.stderr, '\tsum: %e' % sum
if not factor2 == zero:
#if log(term_n, '10') < -1*mpf.dps:
if abs(term_n) < eps:
break
term = term + one
answer = (two * pi) / (sqrt(m) * ellipk(k**2)) * sum
return answer
def jacobi_elliptic_cn(u, m, verbose=False):
"""
Implements the jacobi elliptic cn function, using the expansion in
terms of q, from Abramowitz 16.23.2.
"""
u = convert_lossless(u)
m = convert_lossless(m)
if verbose:
print >> sys.stderr, '\nelliptic.jacobi_elliptic_cn'
print >> sys.stderr, '\tu: %1.12f' % u
print >> sys.stderr, '\tm: %1.12f' % m
zero = mpf('0')
onehalf = mpf('0.5')
one = mpf('1')
two = mpf('2')
if m == zero: # cn collapses to cos(u)
if verbose:
print >> sys.stderr, 'cn: special case, m == 0'
return cos(u)
elif m == one: # cn collapses to sech(u)
if verbose:
print >> sys.stderr, 'cn: special case, m == 1'
return sech(u)
else:
k = sqrt(m) # convert m to k
q = calculate_nome(k)
kprimesquared = one - k**2
kprime = sqrt(kprimesquared)
v = (pi * u) / (two*ellipk(k**2))
sum = zero
term = zero # series starts at zero
if verbose:
print >> sys.stderr, 'elliptic.jacobi_elliptic_cn: calculating'
while True:
factor1 = (q**(term + onehalf)) / (one + q**(two*term + one))
factor2 = cos((two*term + one)*v)
term_n = factor1*factor2
sum = sum + term_n
if verbose:
print >> sys.stderr, '\tTerm: %d' % term,
print >> sys.stderr, '\tterm_n: %e' % term_n,
print >> sys.stderr, '\tsum: %e' % sum
if not factor2 == zero:
#if log(term_n, '10') < -1*mpf.dps:
if abs(term_n) < eps:
break
term = term + one
answer = (two*pi) / (sqrt(m) * ellipk(k**2)) * sum
return answer
def jacobi_elliptic_dn(u, m, verbose=False):
"""
Implements the jacobi elliptic cn function, using the expansion in
terms of q, from Abramowitz 16.23.3.
"""
u = convert_lossless(u)
m = convert_lossless(m)
if verbose:
print >> sys.stderr, '\nelliptic.jacobi_elliptic_dn'
print >> sys.stderr, '\tu: %1.12f' % u
print >> sys.stderr, '\tm: %1.12f' % m
zero = mpf('0')
onehalf = mpf('0.5')
one = mpf('1')
two = mpf('2')
if m == zero: # dn collapes to 1
return one
elif m == one: # dn collapses to sech(u)
return sech(u)
else:
k = sqrt(m) # convert m to k
q = calculate_nome(k)
v = (pi * u) / (two * ellipk(k**2))
sum = zero
term = one # series starts at one
if verbose:
print >> sys.stderr, 'elliptic.jacobi_elliptic_dn: calculating'
while True:
factor1 = (q**term) / (one + q**(two * term))
factor2 = cos(two * term * v)
term_n = factor1 * factor2
sum = sum + term_n
if verbose:
print >> sys.stderr, '\tTerm: %d' % term,
print >> sys.stderr, '\tterm_n: %e' % term_n,
print >> sys.stderr, '\tsum: %e' % sum
if not factor2 == zero:
#if log(term_n, '10') < -1*mpf.dps:
if abs(term_n) < eps:
break
term = term + one
K = ellipk(k**2)
answer = (pi / (two * K)) + (two * pi * sum) / (ellipk(k**2))
return answer
def jacobi_elliptic_dn(u, m, verbose=False):
"""
Implements the jacobi elliptic cn function, using the expansion in
terms of q, from Abramowitz 16.23.3.
"""
u = convert_lossless(u)
m = convert_lossless(m)
if verbose:
print >> sys.stderr, '\nelliptic.jacobi_elliptic_dn'
print >> sys.stderr, '\tu: %1.12f' % u
print >> sys.stderr, '\tm: %1.12f' % m
zero = mpf('0')
onehalf = mpf('0.5')
one = mpf('1')
two = mpf('2')
if m == zero: # dn collapes to 1
return one
elif m == one: # dn collapses to sech(u)
return sech(u)
else:
k = sqrt(m) # convert m to k
q = calculate_nome(k)
v = (pi * u) / (two*ellipk(k**2))
sum = zero
term = one # series starts at one
if verbose:
print >> sys.stderr, 'elliptic.jacobi_elliptic_dn: calculating'
while True:
factor1 = (q**term) / (one + q**(two*term))
factor2 = cos(two*term*v)
term_n = factor1*factor2
sum = sum + term_n
if verbose:
print >> sys.stderr, '\tTerm: %d' % term,
print >> sys.stderr, '\tterm_n: %e' % term_n,
print >> sys.stderr, '\tsum: %e' % sum
if not factor2 == zero:
#if log(term_n, '10') < -1*mpf.dps:
if abs(term_n) < eps:
break
term = term + one
K = ellipk(k**2)
answer = (pi / (two*K)) + (two*pi*sum)/(ellipk(k**2))
return answer
def jdn(u, m):
"""
Computes of the Jacobi elliptic dn function in terms
of Jacobi theta functions.
`u` is any complex number, `m` must be in the unit disk
The dn-function is doubly periodic in the complex
plane with periods `2 K(m)` and `4 i K(1-m)`
(see :func:`ellipk`)::
>>> from mpmath import *
>>> mp.dps = 25
>>> print jdn(2, 0.25)
0.8764740583123262286931578
>>> print jdn(2+2*ellipk(0.25), 0.25)
0.8764740583123262286931578
>>> print chop(jdn(2+4*j*ellipk(1-0.25), 0.25))
0.8764740583123262286931578
"""
if m == zero:
return one
elif m == one:
return sech(u)
else:
extra = 10
try:
mp.prec += extra
q = calculate_nome(sqrt(m))
v3 = jtheta(3, zero, q)
v2 = jtheta(2, zero, q)
v04 = jtheta(4, zero, q)
arg1 = u / (v3*v3)
v1 = jtheta(3, arg1, q)
v4 = jtheta(4, arg1, q)
cn = (v04/v3)*(v1/v4)
finally:
mp.prec -= extra
return cn
def jcn(u, m):
"""
Computes of the Jacobi elliptic cn function in terms
of Jacobi theta functions.
`u` is any complex number, `m` must be in the unit disk
The cn-function is doubly periodic in the complex
plane with periods `4 K(m)` and `4 i K(1-m)`
(see :func:`ellipk`)::
>>> from mpmath import *
>>> mp.dps = 25
>>> print jcn(2, 0.25)
-0.2698649654510865792581416
>>> print jcn(2+4*ellipk(0.25), 0.25)
-0.2698649654510865792581416
>>> print chop(jcn(2+4*j*ellipk(1-0.25), 0.25))
-0.2698649654510865792581416
"""
if abs(m) < eps:
return cos(u)
elif m == one:
return sech(u)
else:
extra = 10
try:
mp.prec += extra
q = calculate_nome(sqrt(m))
v3 = jtheta(3, zero, q)
v2 = jtheta(2, zero, q)
v04 = jtheta(4, zero, q)
arg1 = u / (v3*v3)
v1 = jtheta(2, arg1, q)
v4 = jtheta(4, arg1, q)
cn = (v04/v2)*(v1/v4)
finally:
mp.prec -= extra
return cn
