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c3d / db48x

RPL runtime for the DM42 calculator, in the spirit of HP48/49/50
http://48calc.org
GNU Lesser General Public License v3.0
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SQRT(-1) gives an error message #637

Closed jthole closed 3 weeks ago

jthole commented 7 months ago

Running version 0.5.1 on a DM42:

SQRT(-1) gives me the following error message: "SQRT error: Argument outside domain".

When I enter SQRT(-1 + 0i), I get the correct answer (0 + 1i).

Expected behavior would be, that entering SQRT(-1) gives me (0 + 1i) as result.

c3d commented 7 months ago

This is an expected, but undocumented deviation from HP's RPL.

HP48's will automatically return complex values for real input

HP50 has a -103 flag for real vs. complex results, but the documentation about it is very poor, and it does not seem to impact the result of something like sqrt(-1).

In DB48X, the intent is that a real function will stay in the real domain, under control of a flag that determines if you want complex or real results. Whether I map this flag to -103 or something else is a bit unclear at the moment. I recently added the flag in one of my dev branches, but it's not connected to anything yet.

c3d commented 3 weeks ago

Fixed when implementing #951. This maps to flag -103 as indicated in previous comment. Closing.