Piecewise not defined in SymPy

[dgomezcastro]

I am using SymPy v1.1.6 over Julia v1.7.2 and the piecewise function does not seem to exist, either in lower case or upper case.

It seems that it was implemented at some point: see link

julia> using SymPy

julia> x = Sym("x")
x

julia> piecewise((1, x < 1), (3, x >= 1))
ERROR: UndefVarError: piecewise not defined
Stacktrace:
 [1] top-level scope
   @ REPL[12]:1

julia> Piecewise((1, x < 1), (3, x >= 1))
ERROR: UndefVarError: Piecewise not defined
Stacktrace:
 [1] top-level scope
   @ REPL[15]:1

[mzaffalon]

sympy.Piecewise((1, Lt(x, 1)), (3, Ge(x, 1)))

See here for example.

[dgomezcastro]

Great! That works!. Is there some documentation for this? I cannot find any.

[jverzani]

Maybe the README, but it isn't very front and center. The basic idea is here:

The basic usage follows these points:

generic methods from Julia and imported functions in the sympy namespace are called through fn(object)

SymPy methods are called through Python's dot-call syntax: object.fn(...)

Constructors, like sympy.Symbol, and other non-function calls from sympy are qualified with sympy.Constructor(...). Such qualified calls are also useful when the first argument is not symbolic.

[dgomezcastro]

Perfect. Now I understood the logic. This is very useful.