Refs #14857 add documentation

docs/source/algorithms/IntegratePeaksMD-v2.rst

@@ -97,7 +97,7 @@ IntegrateIfOnEdge option
 ###################################
 
 Edges for each bank or pack of tubes of the instrument are defined by masking the edges in the PeaksWorkspace instrument. 
-e.g. For CORELLI, tubes 1 and 16, and pixels 0 and 255.
+e.g. For TOPAZ pixels 0 and 255 in both directions for the Rectangular Detector.
 Q in the lab frame for every peak is calculated, call it C
 For every point on the edge, the trajectory in reciprocal space is a straight line, going through:
 
@@ -124,6 +124,42 @@ for the integration, one of the detector trajectories on the edge is too close t
 This method is also applied to all masked pixels.  If there are masked pixels trajectories inside an integration volume, the peak must be rejected.
 
    
+CorrectIfOnEdge option
+###################################
+
+This is an extension of what was calculated for the IntegrateIfOnEdge option.  It will only be calculated if this option  
+is true and for the background 
+
+:math:`\left|dv\right|<BackgroundOuterRadius` 
+
+:math:`h = BackgroundOuterRadius - \left|dv\right|`
+
+:math:`r = BackgroundOuterRadius`
+
+or for the peak (assume that the shape is Gaussian)
+
+:math:`\left|dv\right|<PeakRadius`
+
+:math:`\sigma = PeakRadius / 3`
+
+:math:`h = PeakRadius * exp(-\left|dv\right|^2 / (2 \sigma^2)`
+
+:math:`r = PeakRadius`
+
+The minimum of dv is calculated for each peak and from that value the volume of the cap of the sphere is found:
+
+:math:`V_{cap} = \pi h^2 / 3 (3r - h)`
+
+and the volume of the sphere is calculated
+
+:math:`V_{sphere} = 4/3 \pi r^3`
+
+The integrated intensity is multiplied by the ratio of the volume of the sphere divided by the volume where data was collected
+
+:math:`I_{multiplier} = V_{sphere} / (V_{sphere} - V_{cap})`
+
+
+   
 Usage
 ------