Hello Again:

I'm trying to do some clinical research on large data sets and I ran into a problem represented in the following simplified example:
                

geo-> select * from test2;

+-----------+-----------+

| a         | b         |

+===========+===========+

|      3.05 |      3.07 |

|      3.06 |      3.04 |

|      3.13 |      3.16 |

|      3.22 |      3.22 |

|      3.05 |      3.05 |

|      3.07 |      3.06 |

|      3.08 |      3.05 |

|      3.12 |      3.09 |

|      3.20 |      3.17 |

|      3.17 |      3.20 |

|      3.09 |      3.11 |

|      2.74 |      2.73 |

|      2.79 |      2.78 |

|      2.80 |      2.81 |

+-----------+-----------+

               14 rows                

geo-> select * from test2 where a=b;

+-----------+-----------+

| a         | b         |

+===========+===========+

|      3.22 |      3.22 |

|      3.05 |      3.05 |

+-----------+-----------+

2 rows              

geo-> select * from test2 where (a/b)-1=0;

+-----------+-----------+

| a         | b         |

+===========+===========+

|      3.06 |      3.04 |

|      3.22 |      3.22 |

|      3.05 |      3.05 |

|      3.07 |      3.06 |

|      3.08 |      3.05 |

|      3.12 |      3.09 |

|      3.20 |      3.17 |

|      2.74 |      2.73 |

|      2.79 |      2.78 |

+-----------+-----------+

               <>9 rows                

geo-> select * from test2 where (b/a)-1=0;

+-----------+-----------+

| a         | b         |

+===========+===========+

|      3.05 |      3.07 |

|      3.13 |      3.16 |

|      3.22 |      3.22 |

|      3.05 |      3.05 |

|      3.17 |      3.20 |

|      3.09 |      3.11 |

|      2.80 |      2.81 |

+-----------+-----------+

               <>7 rows

I thought that if a=b, then (a/b)-1 and (b/a)-1 must both also be equal to 0.

Columns a and b are type decimal(7,2) and the data was entered to two decimal places by hand using insert statements.

Thanks and best.......George













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