# Configuration¶

## Printing¶

There are three ways to print an expression: # string (mostly for use in the debugger) # unicode (for the python/Ipython command line) # latex (for jupyter notebooks and LaTeX files)

For each way, the output representation of an expression can be changed using the dictionaries str_expr_map, pretty_expr_map, and latex_expr_map. For example, to print the Heaviside “function” as an H instead of the default u, for the LaTeX representation use:

>>> from lcapy.config import latex_expr_map
>>> latex_expr_map[sym.Heaviside] = 'H'


Handling the the imaginary operator sym.I is trickier since this is ingrained as i in SymPy. By default, Lcapy uses j but this can be forced to be printed as i, see lcapy/config.py.

## Parsing¶

Sympy has many predefined symbols. Lcapy ignores the ones listed in config.excludes. For example, N represents the numerical evaluation function. If you wish to have this symbol, remove it from the excludes list, for example,

>>> from lcapy.config import excludes
>>> excludes.remove('N')


Here’s another example, that removes the falling factorial function ff,

>>> from lcapy.config import excludes
>>> excludes.append('ff')