Step 1: Enter a mathematical expression, or alternatively, build the expression using the buttons and tabs located below the Expression box.

Enter the math expression in this box. The syntax is straightforward and based on the C programming language. The expression can contain any combination of functions and operators, absolute and/or variable channel names, DUMMY values, and numbers, spanning multiple equations. The expression can either be directly typed in or built using the supplied Variables and Operators and Functions tabs.

For further details, see the Expression section under Application Notes.

Click this toggle button to expand and display the available Operators and Functions to build the channel math expression. Use the keyboard to enter numerical values.

For more detailed information about the operators and functions of this expanded section, click on the links below:

• Common Keys: Buttons consisting of the most commonly used operations and values, grouped along the left, right below Operators and Functions.

• Frequent Tab: Frequently used conditional and logarithmic operators and functions.

• Special Tab: Special limit and mathematical functions.

• String Tab: String functions. This tab is only visible if your database contains channels of type String.

• Trig Tab: Trigonometric functions.

• Statistics Tab: Statistical properties of one or more lines.

• Offset Tab: Operators to access channel values on rows other than the current one.

• Date Tab: Convert Julian Date (day, month, year) to Geodate (fractional years) or vice versa.

• Time Tab: Convert Time (second, minute, hour) to Geotime (fractional hours) or vice versa.

Click on this button to add a new channel variable at the location of the cursor in the Expression box. The variable channel naming convention is C#, where # is the next available number.

This is not to be confused with temporary variables (see Common Keys), which only exist at run time and are not read from or saved to the database.

Step 2: Assign channels from the current database to the variable names used in the expression.

This box is automatically populated with all the channel variables present in the Expression box. Select from the drop-down list the appropriate channel name to assign to each of the variables in the expression. The drop-down list is populated with the channel names from the current database.

The tool distinguishes between input and output channels. Input channels are preceded by a character and must be selected from a drop-down list, while output channels can be both selected from a list of existing channels and entered manually as a new channel name.

For further details, see the Assign Channels section under Application Notes.

To speed up building the expression, this drop-down list offers a number of simple common math expressions:

• Add 2 Channels: C0 = C1 + C2;

• Divide 2 channels: C0 = C1 / C2;

• Multiply 2 channels: C0 = C1 * C2;

• Multiply channel by factor 2: C0 = C1 * 2;

• Remove 5000 from channel: C0 = C1 - 5000;

• Subtract 2 channels: C0 = C1 - C2;

• True/False statement: C0 = (C1>5000) ? C2 :C3;

You can select an expression from the list and, if needed, continue to further edit it.

Once you have built the expression, you can save it to a file for future use. Similarly, if you have previously saved expressions, you can load them from a file.

The expression files are simple ASCII text files and can be viewed outside of Oasis montaj using a text editor.

Click on Clear to remove all entries, including the expression, grid assignment, and expression file.

Click on Apply to apply the expression without exiting the dialog. This is useful when you intend to apply the same expression to multiple channels in the same database.