Thanks

As you have stated, the third Y column controls the length of the vector. The values in this third Y column are represented as point size in the graph, where 1 point = 1/72 inch on a full 8 1/2 X 11 inch page. There is a procedure that allows you to show vector graphs proportional to the axis scale on the Microcal Software web site under the 'Graphic Hints' heading at:

http://www.microcal.com/www/tech/techdirect.html

This procedure is written for Origin version 5, but can be used in version 4.1 as well. A few things to note when using this procedure in 4.1 are: Right mouse clicks aren't available in version 4.1, so use the set column values button instead. There are no tabs on the dialog boxes, and instead of Tools ptions, select Tools:Preferences.

Vector graphs are actually documented incorrectly in the User's Manual you received with Origin 4.1. The following is a more accurate description of how Origin uses the values entered in the worksheet to create a vector graph.

The User's Manual states that you only need 2 Y columns to create a vector plot. This is not true, you actually need three. The first Y column provides the X, Y coordinates for where the vector will BEGIN (not through the midpoint of the vector, as is stated in the manual). The second Y column provides the angle of the vector. The angle is measured counterclockwise from a line parallel to the X axis (The type of angular unit used is determined by the setting in the Angular Unit group of the Preferences dialog box). The third Y column provides the magnitude of the vector. The values entered in this third column are represented as point size in the graph, where 1 point = 1/72 inch on a full 8 1/2 by 11 inch page.