On 04/01/2021 21:30, Thomas Ligon wrote:
Hello David,
indeed, when I enter print(sqrt(-1)), I get I, just as you do.
However, when I enter print(4s**2), it is flagged with an error
"unexpected token 's'", so I immediately see that I have something
wrong. But, when I enter print(4j**2), I get (-16 + 0j), so python is
just making a complex number out of it, and so I overlooked the error.
Right - I find that rather scary - just accidentally reverting to normal
algebraic notation - means you don't get an error message, but just a
wrong answer - only if you happen to use j in the calculation! I had
always assumed that assigning a variable to a symbol concealed python's
native processing (roughly speaking).
I wonder if there is a way to turn off the 'j' feature in Python. It
really does seem to be something of a hack (in Python, not SymPy) - here
is what I got without importing sympy
>>> 4j
4j
>>> j=0
>>> 4j**2
(-16+0j)
>>> j**2
0
>>> 1j**2
(-1+0j)
David
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