Perfect Mathematics

[RodrigoValentim]

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nvl(grupo.vl_saldo_dev,0) - nvl(grupo.vl_recebido,0) - 0;

Until today I wonder what the -0 serves

[dr_gori]

Cultural moment

In mathematics (algebra), there is the theory of the "neutral element" of operations. (http://pt.wikipedia.org/wiki/Elemento_neutro

Example:
In addition, the neutral element is 0 (can add 0 that remains equal)
in multiplication, is 1 ( If multiplied by 1, remains equal)
and thus all operations have a neutral element.

In the arrays, we have the identity matrix (as below) which is the neutral element of multiplication of matrices. (One can multiply this matrix below by another 2x2 which remains equal)

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| 1   0 | 
| 0   1 |

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| 1   0 |   x  |  5   3 |   =  |  5   3 | 
| 0   1 |      |  2   9 |      |  2   9 | 

and so on! [ 99]
(now ask me to know that? I'm trying to figure out )