On 7 July 2010 18:59, Evert Rol <evert....@gmail.com> wrote: > > The second number should be negative ( I WANT it to be negative). For > example: > > > > print (0 - t[4])*(t[3] - t[5]) , (0 - t[5])*(t[2] - t[4]) gives : > > > > -30895 -935636 > > > > And in the python shell: > > > > >>> -30895 -935636 > > -966531 > > No, because you have to *subtract* the second answer from the first ( > according to your print statement: print (0 - t[4])*(t[3] - t[5]) - (0 - > t[5])*(t[2] - t[4]) ). So: > >>> -30895 - -935636 > 904741 > > > If you want it to be negative, check the order of your coordinates: maybe > you need to interchange two variables between one set of parentheses. Or > maybe you need to subtract absolute values instead (sorry, too lazy to do > the math to find out what is correct). >
Yes, it's so simple isn't it? The old double negative. Thanks a lot for your prompt reply, great.
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