I apologize for not reproducing it earlier as I quickly found a simple example.
In the process of transforming coordinates, X is R * cos(THETA) where R was zero(0)
and THETA was 3.1415.
| ?- R is 0, THETA is 3.1415, X is R * cos(THETA).
R = 0
THETA = 3.1415000000000002
X = -0.0
| ?-
In the debugger this turns out to be -0.0 is (0 * -0.99999999570765619).
Dave
--- On Mon, 2/16/09, Daniel Diaz <address@hidden> wrote:
From: Daniel Diaz <address@hidden>
Subject: Re: -0.0 versus 0.0
To: address@hidden
Cc: address@hidden
Date: Monday, February 16, 2009, 6:31 AM
Dave, think this is due to rounding and/or how floats are displayed by default. Could you try to reproduce it please ? Thank you Dave Sworin a écrit :
|
Sometimes a variable, after lots of calculations, is instantiated to a
float value of -0.0 in the gprolog interpreter. When I compare the
variable to 0.0, as in X =:= 0.0, it succeeds. X < 0.0 fails. What
is the significance of the minus sign? Is the return of -0.0 intentional?
I don't have a simple example as this usually occurs after some
matrix operations with lots of additions and multiplications.
Dave
|
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