### Calculated Column Custom Expression Details

• An expression must be a number, a data column, an appropriately formatted function, or a combination of these items: [5, “X”, sin(“X”), 5sin(“X”)]
• Supported operators are + – * / ^ ( )
• Functions must contain their arguments in parentheses. [abs(“X”) or sqrt(2)]
• Multiplication can be explicit and implied. [5*“X”or 5“X” or 5(“X”)]
• Constants must be entered as numbers. Variable parameters (e.g., A, B, C) are not supported.
• Trigonometric functions are evaluated in radians.
• Functions can be nested as long as the proper format is used. [sqrt(abs(“X”))]

### Function Syntax

Below is a list of available functions and their syntax when using the Custom Expression option for Graphical Analysis Pro calculated columns.

### Digital Filter Functions

Digital Filter functions are designed to work with analog sensors and/or truly analog signals. Signals or sensors that perform digital signal processing may not work well with these features.

The Digital Filter functions have the following parameters:

• “Y” – a column of data to which the filter is being applied
• “X” – the independent variable column for your data; typically Time
• cutoff [lowCutoff, highCutoff] – the FFT frequency cutoff value used for the filter; must be a number
• bandPassRipple – Optional value; must be a number
• This value is the percentage of pass-band
• Low Pass and High Pass filters are 0, which applies a Butterworth pass filter, unless otherwise specified.
• Band Stop and Band Pass are 0.5 unless otherwise specified.

### Derivative Functions

Derivative functions are designed to find the numerical rate of change of a variable with respect to another variable, typically time. The numerical derivative is the weighted average of the slope of ‘n’ points around each point, where ‘n’ is the numberOfPoints parameter noted below.

The Derivative functions have the following parameters: