This file contains a description of the usage of the scale factor
between layers.

The scale factor is a measure of the difference in distance scales between
layers.  The distance scale, dx, is the distance between neurons in
retinatopic units so dx in the retina is 1.

In the PV code, the scale factor is usually stored as log base 2 of the
relative scale factor.  Thus if xScaleLog2 == 1 for a layer, then dx == 2
(the linear density of neurons is 1/2 that of the retina).  Likewise if
xScaleLog2 == -1, then dx == 1/2 (the linear density of the neurons is 2 times
that of the retina).

This file contains a description of the usage of the scale factor
between layers.

The scale factor is a measure of the difference in distance scales between
layers.  The distance scale, dx, is the distance between neurons in
retinatopic units so dx in the retina is 1.

A column's nx and ny give the base number of neurons in each direction for
the column. 

Each layer's nxScale and nyScale gives that layer's neuron density relative
to that of the column.  So, if the column's nx is 32 and the layer's nxScale
is 0.5, the layer will have 16 neurons in the x-direction and dx=2.

In the PV code, the scale factor is usually stored as log base 2 of the
relative scale factor.  Thus if nxScale = 0.5 for a layer L, then
L->xScale == 1, and dx == 2 (the linear density of neurons is 1/2 that of
the retina).  Likewise if L->xScale == -1, then dx == 1/2 (the linear
density of the neurons is 2 times that of the retina).

The scale factor is an integer.  If the user-supplied nxScale is not an
integer power of two, xScale will be the integer nearest log2(nxScale).

Clarify the relation between params file's nxScale,nyScale and internal xScale,yScale
Clarify the relation between params file's nxScale,nyScale and internal xScale,yScale

git-svn-id: 602a26e73ae9f2a14e2bb95676f2e137fcc39919@3811 7c0444ca-5550-0410-9008-faecdbe78eb5
