--- ray/doc/man/man1/gendaymtx.1	2014/05/30 00:00:54	1.6
+++ ray/doc/man/man1/gendaymtx.1	2019/06/25 00:09:45	1.10
@@ -1,4 +1,4 @@
-.\" RCSid $Id: gendaymtx.1,v 1.6 2014/05/30 00:00:54 greg Exp $
+.\" RCSid $Id: gendaymtx.1,v 1.10 2019/06/25 00:09:45 greg Exp $
 .TH GENDAYMTX 1 01/19/13 RADIANCE
 .SH NAME
 gendaymtx - generate an annual Perez sky matrix from a weather tape
@@ -9,6 +9,8 @@ gendaymtx - generate an annual Perez sky matrix from a
 ][
 .B "\-h"
 ][
+.B "\-A"
+][
 .B "\-d|\-s"
 ][
 .B "\-r deg"
@@ -53,9 +55,17 @@ Thus, an hourly weather tape for an entire year would
 yield 8760x3 (26280) values per output line (row).
 .PP
 The
+.I \-A
+option tells
+.I gendaymtx
+to generate a single column corresponding to an average sky
+computed over all the input time steps, rather than one
+column per time step.
+.PP
+The
 .I \-c
 option may be used to specify a color for the sky.
-The gray value should equal 1 for proper energy balance
+The gray value should equal 1 for proper energy balance.
 The default sky color is
 .I "\-c 0.960 1.004 1.118".
 Similarly, the
@@ -67,10 +77,16 @@ corresponding to a 20% gray.
 .PP
 The
 .I \-d
-option may be used to produce a sun-only matrix, with no sky contributions.
+option may be used to produce a sun-only matrix, with no sky contributions,
+and the ground patch also set to zero.
 Alternatively, the
 .I \-s
-option may be used to exclude any direct solar component from the output.
+option may be used to exclude any direct solar component from the output,
+with the rest of the sky and ground patch unaffected.
+If there is a sun in the description,
+.I gendaymtx
+will include its contribution in the four nearest sky patches,
+distributing energy according to centroid proximity.
 .PP
 By default,
 .I gendaymtx