Expression system#

Classes#

`expression`	Class to represent symbolic expressions.
`dtens`	Class to store derivative tensors.

`make_vars`(*args)	Create variable expressions from strings.
`diff_tensors`(func, diff_args[, diff_order])	Compute the tensors of derivatives.
`subs`(arg, smap)	Substitution.
`sum`(terms)	Multivariate summation.
`prod`(terms)	Multivariate product.

Parameter factory.

Enum for selecting differentiation arguments.