--- ray/doc/man/man1/dctimestep.1	2019/10/23 17:00:14	1.16
+++ ray/doc/man/man1/dctimestep.1	2022/03/11 02:27:02	1.17
@@ -1,4 +1,4 @@
-.\" RCSid $Id: dctimestep.1,v 1.16 2019/10/23 17:00:14 greg Exp $"
+.\" RCSid $Id: dctimestep.1,v 1.17 2022/03/11 02:27:02 greg Exp $"
 .TH DCTIMESTEP 1 12/09/09 RADIANCE
 .SH NAME
 dctimestep - compute annual simulation time-step(s) via matrix multiplication
@@ -11,6 +11,10 @@ dctimestep - compute annual simulation time-step(s) vi
 ][
 .B "\-o ospec"
 ][
+.B "\-x xres"
+][
+.B "\-y yres"
+][
 .B "\-i{f|d}
 ][
 .B "\-o{f|d|c}
@@ -122,6 +126,13 @@ If the given specification contains a '%d' format stri
 will be replaced by the time step index, starting from 0.
 In this way, multiple output pictures may be produced,
 or separate result vectors (one per time step).
+If input is a matrix rather than a set of images, the
+.I \-x
+and/or
+.I \-y
+options may be necessary to set the output image size.
+If only one dimension is specified, the other is computed based
+on the number of rows in the result vectors.
 .PP
 A header will normally be produced on the output, unless the
 .I \-h