LOG2

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Syntax

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Scalar

log2(value)

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Arguments

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Returns

• Type: DOUBLE; FLOAT when the input is evaluated as FLOAT
• Possible values: Real logarithms for positive input; negative infinity at zero and NaN for negative input.
• NULL behavior: Returns NULL when an argument is NULL.

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Properties

• Approximation bound: No fixed maximum error is guaranteed.

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Usage notes

• Numeric inputs are normally converted to DOUBLE for calculation. An input evaluated as FLOAT keeps FLOAT precision.
• INTEGER and INT mean the same type; STRING means VARCHAR text. NULL can be used with a supported type. Cast NULL explicitly when its type would otherwise be unclear.
• Exact result: Floating-point computation can round the mathematical result.

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Examples

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Value and NULL input

SELECT log2(CAST(1 AS DOUBLE)) AS "value", log2(CAST(NULL AS DOUBLE)) AS null_value;

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Values below and above one

SELECT round(log2(CAST(0.5 AS DOUBLE)), 6) AS below_one, round(log2(CAST(8 AS DOUBLE)), 6) AS above_one;

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Limitations

• Zero returns negative infinity; negative input returns NaN.
• The result is FLOAT when the input is evaluated as FLOAT, and DOUBLE after other numeric conversions. Query tools may report the original input type instead; this does not convert the result back to INTEGER or DECIMAL.