[Groff] Extra newlines in matrix equation

[Andy Spencer]

I'm trying to use groff to format a matrix equation using the eqn
preprocessor. I seem to be getting a lot of extra blank lines in the
output. Does anyone know what could be causing this?

Here's the input file:

  > .TH "MATRIX"
  > .SH "DESCRIPTION"
  > .PP
  > A matrix:
  > .PP
  > .EQ
  >  matrix { ccol { x above 0 above 0 } ccol { 0 above y above 0 } ccol { 0 
above 0 above z } }
  > .EN


Here's the command I'm running:

  > eqn -Tascii matrix.1 | nroff -man > matrix.tx


And here's the output, after removing ANSI escape codes:

  > MATRIX()                                                              
MATRIX()
  > 
  > 
  > 
  > DESCRIPTION
  >        A matrix:
  >        x 0 0
  > 
  > 
  > 
  > 
  > 
  > 
  > 
  > 
  > 
  > 
  > 
  > 
  > 
  > 
  > 
  > 
  > 
  > 
  > 
  >        0 y 0
  > 
  > 
  > 
  > 
  > 
  > 
  > 
  > 
  > 
  > 
  > 
  > 
  > 
  > 
  > 
  > 
  > 
  > 
  > 
  >        0 0 z