Perform floating point math with two table files. (or one table file and a constant value).

% oned_imarith.sh
Usage: oned_imarith.sh a.1 - b.1 o.file 
arg1 - input file 1
arg2 - operation (-,+,/,x) 
arg3 - input FITS file 2 
arg4 - output file name 
arg5 - include header flag on output (Y/N) 

% oned_imarith.sh --help 
oned_imarith:
 This OTW code is the 1-D analog to clip_imarith. It takes as input two 
files of numerical data *like those generated with codes like gen_curve 
and gen_noise) and combines the values (line by line) using simple math
operators. 

 In general this code take two input files, each having a "# data# header. 
The numerical values on each set of lines is compined using the operator
specified by arg2. The specifies the name of the output file (arg4) and 
whether or not that file will have a "# data" header (arg5). 

---------------------------------------------------
A very simple example. 
% cat a.1
# data 
1
2
3
4
% cat b.1
# data
2.0
2.0
2.0
2.0
% oned_imarith.sh a.1 x b.1 o.file N
% cat o.file 
      2.0000000
      4.0000000
      6.0000000
      8.0000000
---------------------------------------------------

  Sometimes we simpley want to use a fixed constant as the second 
numerial value. You can do this by enetring the fixed number as the 
name of the second file (arg3). Here is an example:

---------------------------------------------------
A very simple example. 
% cat a.1
# data 
1
2
3
4
% oned_imarith.sh a.1 x 3.3 o.file Y 
% cat o.file
# file 1 = a.1                                                                                                                     
# Operation  = x
# file 2 = 3.3                                                                                                                     
# data
      3.3000000
      6.5999999
      9.8999996
     13.1999998
---------------------------------------------------