fltfiles - format for digital filter files (as well as being one)

# This is a filter file. It specifies the order and coefficients of
# an order 4 IIR filter. 
#
# Note that `#' means that the rest of the line is a comment.
# The very first non-comment word in a filter file must be `filter'.
# All other parameters may be omitted to obtain their default values.
# In all commands, case is not important. 
#
# Here is a complete filter specification:
#

Filter;		# Mandatory first word 
NICoeffs = 4;	# Number of Input Coefficients (default = 1)
NOCoeffs = 2;	# Number of OutputCcoefficients (default = 1)
ICoeffs =  	# Input coefficients. Note that newlines are ignored.
  .917123407e-01  .332813461e+00  .454923451e+00  .332813561e+00
;		# Actually semicolons are not required nor are the = signs.
Type = TDL;	# Tapped Delay Line filters are the only type at present.
OCoeffs = 1.0  -0.9; 	# The first Output Coefficient must ALWAYS be 1.

# This concludes the general example of a filter file.
# Actually, when rolling our own by hand, we would be more likely to say simply:
 
# filter;  ni 4 no 2
# ic .917123407e-01  .332813461e+00  .454923451e+00  .332813561e+00
# oc 1 -.9
# But of course without the preceding `#' signs.
 
# In general, commands (such as IC) are terminated by any character
# other than the alphabet, and values (such as 5) are terminated by anything
# other than the alphabet or numbers 0 through 9 or "+-." .
# Commands may be abbreviated as long as they are unambigous. 
 
# The subroutine which reads this filter file is called `getflt'.
# An example of a main program
# which calls getflt and actually uses the filter is filter.c .
