exp

Use the exp function in APL to compute the base-e exponential of a value: e^x. It's the inverse of the natural logarithm function log.

exp is useful when you work with log-transformed data and need to recover the original scale. For example, if you have computed the average of log-transformed latencies and want the geometric mean on the original scale, apply exp to the result. You can also use exp to model exponential growth or decay in metric data.

Usage

Syntax

exp(x)

Parameters

Returns

The base-e exponential of x: e^x.

Example

Use exp to compute the geometric mean of request durations from log-transformed values.

Query

['sample-http-logs']
| where req_duration_ms > 0
| summarize geometric_mean = exp(avg(log(req_duration_ms))) by bin(_time, 1h)
| project _time, geometric_mean

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Output

List of related functions

• log: Returns the natural logarithm. Use it as the inverse of exp or to apply log transformations before aggregating.
• exp2: Returns 2^x. Use it instead of exp when working with binary (base-2) scales.
• exp10: Returns 10^x. Use it instead of exp when working with base-10 (decibel or order-of-magnitude) scales.
• pow: Raises any base to a power. Use it when the base isn't e, 2, or 10.
• sqrt: Returns the square root. Use it for simpler power-of-0.5 calculations rather than exp(0.5 * log(x)).

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