Index: src/sas/qtgui/Perspectives/Inversion/InversionPerspective.py
===================================================================
--- src/sas/qtgui/Perspectives/Inversion/InversionPerspective.py	(revision b0ba43ee4b198d4f5a834c93888985b18c20c071)
+++ src/sas/qtgui/Perspectives/Inversion/InversionPerspective.py	(revision b0ba43ee4b198d4f5a834c93888985b18c20c071)
@@ -376,5 +376,5 @@
         Open the P(r) Inversion help browser
         """
-        tree_location = "/user/sasgui/perspectives/pr/pr_help.html"
+        tree_location = "/user/qtgui/Perspectives/Inversion/pr_help.html"
 
         # Actual file anchor will depend on the combo box index
Index: src/sas/qtgui/Perspectives/Inversion/media/pr_help.rst
===================================================================
--- src/sas/qtgui/Perspectives/Inversion/media/pr_help.rst	(revision 417c03f075685f86777838c8c717dec8e0ed8965)
+++ src/sas/qtgui/Perspectives/Inversion/media/pr_help.rst	(revision 417c03f075685f86777838c8c717dec8e0ed8965)
@@ -0,0 +1,96 @@
+.. pr_help.rst
+
+.. This is a port of the original SasView html help file to ReSTructured text
+.. by S King, ISIS, during SasView CodeCamp-III in Feb 2015.
+
+P(r) Calculation
+================
+
+Description
+-----------
+
+This tool calculates a real-space distance distribution function, *P(r)*, using
+the inversion approach (Moore, 1980).
+
+*P(r)* is set to be equal to an expansion of base functions of the type
+
+.. math::
+  \Phi_{n(r)} = 2 r sin(\frac{\pi n r}{D_{max}})
+
+The coefficient of each base function in the expansion is found by performing
+a least square fit with the following fit function
+
+.. math::
+
+  \chi^2=\frac{\sum_i (I_{meas}(Q_i)-I_{th}(Q_i))^2}{error^2}+Reg\_term
+
+
+where $I_{meas}(Q_i)$ is the measured scattering intensity and $I_{th}(Q_i)$ is
+the prediction from the Fourier transform of the *P(r)* expansion.
+
+The $Reg\_term$ term is a regularization term set to the second derivative
+$d^2P(r)/d^2r$ integrated over $r$. It is used to produce a smooth *P(r)* output.
+
+.. ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ
+
+Using P(r) inversion
+--------------------
+
+The user must enter
+
+*  *Number of terms*: the number of base functions in the P(r) expansion.
+
+*  *Regularization constant*: a multiplicative constant to set the size of
+   the regularization term.
+
+*  *Maximum distance*: the maximum distance between any two points in the
+   system.
+
+P(r) inversion requires that the background be perfectly subtracted.  This is
+often difficult to do well and thus many data sets will include a background.
+For those cases, the user should check the "Estimate background level" option
+and the module will do its best to estimate it. If you know the background value
+for your data, select the "Input manual background level" option. Note that
+this value will be treated as having 0 error.
+
+The P(r) module is constantly computing in the background what the optimum
+*number of terms* should be as well as the optimum *regularization constant*.
+These are constantly updated in the buttons next to the entry boxes on the GUI.
+These are almost always close and unless the user has a good reason to choose
+differently they should just click on the buttons to accept both.  {D_max} must
+still be set by the user.  However, besides looking at the output, the user can
+click the explore button which will bring up a graph of chi^2 vs Dmax over a
+range around the current Dmax.  The user can change the range and the number of
+points to explore in that range.  They can also choose to plot several other
+parameters as a function of Dmax including: I0, Rg, Oscillation parameter,
+background, positive fraction, and 1-sigma positive fraction.
+
+.. ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ
+
+.. _Batch_Pr_Mode:
+
+Batch P(r) inversion
+--------------------
+
+The p(r) calculator accepts any number of data sets, and supports batch fitting
+for all data sets in the p(r) data set combo box. Switching between data sets in
+the combo box allows for individual fits and review of fit parameters. The
+displayed plots will also update to include the latest fit results for the
+selected data set.
+
+The 'Calculate All' button will run the p(r) calculation for each file,
+sequentially. The calculator will estimate the number of terms, background, and
+regularization constant for each file prior to running the p(r) calculation.
+The final results for all data sets are then presented in a savable data table.
+
+.. ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ
+
+Reference
+---------
+
+P.B. Moore
+*J. Appl. Cryst.*, 13 (1980) 168-175
+
+.. ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ
+
+.. note::  This help document was last modified by Jeff Krzywon, 18 April 2018
