Type directly in the box and then click Update, or add terms to the equation by selecting them in the following drop-down lists:

Select terms to add to the equation, which appears in the top box of the Compose an Equation pane, by selecting terms from the drop-down lists.

Either select a function to modify from the Log Equation Library, or click Edit to launch the Log Equation Library dialog box with which you compose the desired equation.

Associate logs with equation variables defined above and after selecting the desired depth range below, click Create New Log.

Variables you typed in your equation above that haven't been defined yet appear here.

Do one of the following:
Type start and stop depths and click Update.
Click either Top or Bottom to select an absolute depth from the log or click All to select both.
Click Depths from tops to select a range using the formation top names that also appear in the tops list selected in the Top Properties dialog box.

Select to reset the log scales based on the resulting data range. This will reset the log scale so that the resulting display isn't blank. Clear this option to maintain a preferred or industry-standard log scales as you might with sonic logs, for example.