# eval

The delta operator evaluates a time series based on a user-specified math expression.

Evaluates a time series based on a user-specified math expression.

### eval syntax

*metrics query* | eval <*math expression*>

where `<`

is a valid math expression with *math expression*>`_value`

as the placeholder for each data point in the time series.

Supported Basic operations:

`+, -, *, /`

Supported Math functions:

`sin, cos, abs, log, round, ceil, floor, tan, exp, sqrt, min, max`

### Eval examples

#### Multiply a metric

This query returns the value of the `cpu_idle`

metric, multiplied by 100.

`_sourceCategory=ApacheHttpServer metrics=cpu_idle | eval _value * 10`

*Tags recommended by the template: *article:topic