/*********************************************************************
* jsim_n 3/8/95	                                                     *
* stochastic extension of jsim.                                      *
*                                                                    *
* Modifications by J. Satchell (satchell@dra.hmg.gb)                 *
* Files that have been altered have "_n" at the end of the first     *
* component of their names. The modifications, the makefile, this    *
* README, the documentation file noise.ms, the awk script noise.awkf *
* and the contents of the tests  directory are all covered by the    *
* following copyright                                                *
*                                                                    *
*  (c) British Crown copyright January 1997/DERA.                    *
*  Permission to use, copy, modify, and distribute this software     * 
*  and documentation for any purpose without fee is hereby granted,  *
*  provided that the above copyright notice appears in all copies    *
*  The copyright holders make no representations about the           *
*  suitability of this software for any purpose. It is provided      *
*  "as is" without express or implied warranty. No liability is      *
*  accepted by the copyright holder for any use made of this         *
*  software                                                          *
*                                                                    *
* See below for revised make instructions                            *
*                                                                    *
**********************************************************************/ 
/** _n **/
See the original README file, which I have renamed README.old.
I don't think I have anything to add to it, except I have removed the dos 
make files as they would need modifications that I am not competent to make.

I have made a dumb makefile, which does not need the subsidiary ones in
the subdirectories. It also doesn't bother with ar or ranlib.

So now to implement, just edit makefile, (e.g change cc to gcc).
If you are on a machine which does not support random() in its c library,
set -DNORANDOM, and the horrible function rand() will be used. This is
a low quality random number generator, with a spectrum which is 
coloured, but is supported on almost all machines. Alternatively
see if your system supports srand48/drand48, and edit the source code
to use those instead.

To improve the interactive feel of my graphics I have added
extra flushing statements, which will incur a small IO
overhead. If this bothers you, comment out the calls to fflush
in file jsimtxt/tran_n.c

An awk script has been provided which adds noise to circuit,
by including noise current source across every resistor.
To use it on a file circuit.js you could try

awk -f noise.awkf temperature=77.36 < circuit.js | jsim_n

As far as I know any of awk, nawk and gawk are OK. If you are 
using DOS/Windoze, you are stuck, unless there is a DOS awk 
implementation available somewhere on the net. The script is simple
enough that it could be emulated by some other programme if need be.
 
Resistors whose names start with Z are left alone, so you can 
add noise free bias networks, output filters and the like.

There are some tests in the tests subdirectory.


Julian Satchell (satchell@dra.hmg.gb)        (+44) 1684 895003