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nan [Sun Oct 31 19:04:52 2010] Gray |
nan [Sun Oct 31 19:06:53 2010] Gray |
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An invalid operation is not the same as an arithmetic overflow (which returns a positive or negative infinity). Arithmetic operations involving NaN always produce NaN, allowing the value to propagate through a calculation so that errors can be detected at the end without extensive testing during intermediate stages. | An invalid operation is not the same as an arithmetic overflow (which returns a positive or negative infinity). Arithmetic operations involving NaN always produce NaN, allowing the value to propagate through a calculation so that errors can be detected at the end without extensive testing during intermediate stages. | ||
- | A NaN does not compare equal to any number or NaN. You can therefore test whether a variable has a NaN value by comparing it to itself, therefore, | + | A NaN does not compare equal to any number or NaN. You can therefore test whether a variable has a NaN value by comparing it to itself: if '' |
==== How does a NaN appear? ==== | ==== How does a NaN appear? ==== | ||
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=== Example === | === Example === | ||
- | * If you set [[set_column_formula|Column Formula]] '' | + | * If you set a [[set_column_formula|Column Formula]] '' |