Analyze g Area above X axis (shift-F10)
Calculates the area of a selected plot above the X-axis between a given range. The area appears at the top of the graph. SumY means the sum of all Y values between the given range, Area gives the actual area (calculated by the sum of the width x height of every data point in the range).
To avoid overvaluation of the area, it is calculated between two data points. The average Y value of two adjacent data points is calculated, and this is multiplied by the distance of the two data points. This will result in a difference between the sumY value and the area when the width is 1.
Of the above plot SumY = 15 and Area = 10.5
Analyze g Area above line, peak area (F10)
You draw a line between two points by clicking on the graph once for each point, and then the program calculates the area of the selected plot above this line. You can move the line around by dragging its end points. If snap to plot is active before peak area is selected, the end points will snap to the nearest data point after dragging.
You can select different plots (by double clicking on the names at the right side) while the same line stays active. Every time when just one data set is selected, the area above the line is calculated and displayed. When more than one set is selected, the display disappears, to re-appear again when just one set is selected. This makes it easy to switch between plots while leaving the same line active.