split_expression function¶
(Shortest import: from brian2.stateupdaters.explicit import split_expression)
-
brian2.stateupdaters.explicit.
split_expression
(expr)[source]¶ Split an expression into a part containing the function
f
and another one containing the functiong
. Returns a tuple of the two expressions (as sympy expressions).Parameters: expr : str
An expression containing references to functions
f
andg
.Returns: (non_stochastic, stochastic) : tuple of sympy expressions
A pair of expressions representing the non-stochastic (containing function-independent terms and terms involving
f
) and the stochastic part of the expression (terms involvingg
and/ordW
).Examples
>>> split_expression('dt * __f(__x, __t)') (dt*__f(__x, __t), None) >>> split_expression('dt * __f(__x, __t) + __dW * __g(__x, __t)') (dt*__f(__x, __t), __dW*__g(__x, __t)) >>> split_expression('1/(2*dt**.5)*(__g_support - __g(__x, __t))*(__dW**2)') (0, __dW**2*__g_support*dt**(-0.5)/2 - __dW**2*dt**(-0.5)*__g(__x, __t)/2)