162 lines
4.2 KiB
Python
162 lines
4.2 KiB
Python
"""
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The classes in this module are designed to allow constructing
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user-defined functions of one variable in Python that can be used with the
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Cantera C++ kernel. These classes are mostly shadow classes for
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corresponding classes in the C++ kernel.
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"""
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from Numeric import array, asarray, ravel, shape, transpose
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import _cantera
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import types
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class Func1:
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"""Base class for functions of one variable."""
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def __init__(self, typ, n, coeffs=[]):
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self.n = n
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self.coeffs = asarray(coeffs,'d')
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self._func_id = _cantera.func_new(typ, n, self.coeffs)
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def __del__(self):
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_cantera.func_del(self._func_id)
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def __call__(self, t):
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"""Implements function syntax, so that F(t) is equivalent to
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F.value(t)."""
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return _cantera.func_value(self._func_id, t)
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def __add__(self, other):
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"""Overloads operator '+'
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Returns a new function self(t) + other(t)"""
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if type(other) == types.FloatType:
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return SumFunction(self, Const(other))
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return SumFunction(self, other)
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def __radd__(self, other):
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"""Overloads operator '+'
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Returns a new function other(t) + self(t)"""
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if type(other) == types.FloatType:
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return SumFunction(Const(other),self)
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return SumFunction(other, self)
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def __mul__(self, other):
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"""Overloads operator '*'
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Return a new function self(t)*other(t)"""
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return ProdFunction(self, other)
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def __rmul__(self, other):
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"""Overloads operator '*'
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Returns a new function other(t)*self(t)"""
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return ProdFunction(other, self)
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def __div__(self, other):
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"""Overloads operator '/'
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Returns a new function self(t)/other(t)"""
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return RatioFunction(self, other)
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def __rdiv__(self, other):
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"""Overloads operator '/'
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Returns a new function other(t)/self(t)"""
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return RatioFunction(other, self)
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def func_id(self):
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return self._func_id
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class Polynomial(Func1):
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"""A polynomial. The degree is determined by the number of coefficients
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supplied. Examples:
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p1 = Polynomial([1.0, -2.0, 3.0]) # 3t^2 - 2t + 1
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p2 = Polynomial([6.0, 8.0]) # 8t + 6
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"""
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def __init__(self, coeffs=[]):
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Func1.__init__(self, 2, len(coeffs)-1, coeffs)
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class Fourier(Func1):
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"""
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Fourier series.
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f(t) = a[0]/2 + sum_{i=1}^n [a[i]*cos(n*omega*t) + b[i]*sin(n*omega*t)]
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Note that b[0] must be specified for symmetry with 'a', but is not
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used.
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Example:
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coeffs = [(a0, b0), (a1, b1), (a2, b2)]
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f = Fourier(omega, coeffs)
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"""
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def __init__(self, omega, c):
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cc = asarray(c,'d')
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n, m = cc.shape
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if m <> 2:
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raise CanteraError('provide (a, b) for each term')
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cc[0,1] = omega
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Func1.__init__(self, 1, n-1, ravel(transpose(cc)))
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class Arrhenius(Func1):
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"""Sum of modified Arrhenius terms.
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f(T) = \sum_{i=1}^n A_n T^{b_n}\exp(-E_n/T)
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Example:
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f = Arrhenius([(a0, b0, e0), (a1, b1, e1)])
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"""
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def __init__(self, c):
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cc = asarray(c,'d')
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n, m = cc.shape
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if m <> 3:
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raise CanteraError('Three Arrhenius parameters (A, b, E) required.')
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Func1.__init__(self, 3, n, ravel(cc))
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def Const(value):
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"""Constant function."""
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return Polynomial([value])
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# functions that combine two functions
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class SumFunction(Func1):
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"""f = f1 + f2"""
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def __init__(self, f1, f2):
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self.f1 = f1
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self.f2 = f2
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self.n = -1
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self._func_id = _cantera.func_newcombo(20, f1.func_id(), f2.func_id())
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class ProdFunction(Func1):
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"""f = f1 * f2"""
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def __init__(self, f1, f2):
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self.f1 = f1
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self.f2 = f2
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self.n = -1
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self._func_id = _cantera.func_newcombo(30, f1.func_id(), f2.func_id())
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class RatioFunction(Func1):
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"""f = f1 / f2"""
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def __init__(self, f1, f2):
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self.f1 = f1
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self.f2 = f2
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self.n = -1
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self._func_id = _cantera.func_newcombo(40, f1.func_id(), f2.func_id())
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