function_library.py

# This file is part of the UFO.
#
# This file contains definitions for functions that
# are extensions of the cmath library, and correspond
# either to functions that are in cmath, but inconvenient
# to access from there (e.g. z.conjugate()),
# or functions that are simply not defined.
#
#
 
__date__ = "22 July 2010"
__author__ = "claude.duhr@durham.ac.uk"
 
import cmath
from object_library import all_functions, Function
 
#
# shortcuts for functions from cmath
#
 
complexconjugate = Function(name = 'complexconjugate',
                            arguments = ('z',),
                            expression = 'z.conjugate()')
 
 
re = Function(name = 're',
              arguments = ('z',),
              expression = 'z.real')
 
im = Function(name = 'im',
              arguments = ('z',),
              expression = 'z.imag')
 
# New functions (trigonometric)
 
sec = Function(name = 'sec',
             arguments = ('z',),
             expression = '1./cmath.cos(z)')
 
asec = Function(name = 'asec',
             arguments = ('z',),
             expression = 'cmath.acos(1./z)')
 
csc = Function(name = 'csc',
             arguments = ('z',),
             expression = '1./cmath.sin(z)')
 
acsc = Function(name = 'acsc',
             arguments = ('z',),
             expression = 'cmath.asin(1./z)')
 
cot = Function(name = 'cot',
               arguments = ('z',),
               expression = '1./cmath.tan(z)')
 
# Heaviside theta function
 
theta_function = Function(name = 'theta_function',
             arguments = ('x','y','z'),
             expression = 'y if x else z')
 
# Auxiliary functions for NLO
 
cond = Function(name = 'cond',
                arguments = ('condition','ExprTrue','ExprFalse'),
                expression = '(ExprTrue if condition==0.0 else ExprFalse)')
 
reglog = Function(name = 'reglog',
                arguments = ('z'),
                expression = '(0.0 if z==0.0 else cmath.log(z))')