Type directly in the box and then click Update. Terms you type appear in the Log type boxes below and you associate the terms with logs by selecting the desired log from the Index Log drop-down list to the right of the Log type box.

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

View the constructed formula that will be applied.

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

Select log types to associate with terms in your equation.

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.