This app can be used to estimate the onset of slope change in a data plot.

Purpose:
This app allows you to place up to four "region-of-interest" (ROI) objects on a graph, and perform a linear regression of data points within each ROI.  Each ROI should delineate a line segment of uniform slope. The app then calculates the intersection points of adjacent linear regression lines.

Installation:
Download the Onset Of Slope.opx file and then drag and drop it into Origin workspace to install it. A new app icon named Onset Of Slope will be added to your Apps Gallery.

Operation:

1. With a line/scatter graph active, click the Onset Of Slope icon.
2. Select the number of rectangles and optionally set other properties in the dialog, and press OK to close.
3. Move/resize rectangles to define your regions of interest (ROI).
4. Click on the arrow button in the ROI control, and select Tag Lines to add lines, intersection points, and labels to the graph. Continue tagging other parts of the curve as desired.
5. Close the gadget by pressing on the '''X''' button.
6. The tagged results will stay on the graph. The data for the lines and intersection points will be added as a new sheet to the workbook containing the graphed data.

v1.1: Fixed some bugs, such as masked data, label position, tag line for OGG, etc.
v1.2: Fixed bug for tagging wrong intersected point.