/* CHANNEL.H - Declarations regarding channels. *//* Copyright (c) 2001 by Radford M. Neal  * * Permission is granted for anyone to copy, use, or modify this program  * for purposes of research or education, provided this copyright notice  * is retained, and note is made of any changes that have been made.  * * This program is distributed without any warranty, express or implied. * As this program was written for research purposes only, it has not been * tested to the degree that would be advisable in any important application. * All use of this program is entirely at the user's own risk. *//* TYPES OF CHANNEL, AND CHANNEL PARAMETERS.  The global variables declared   here are located in channel.c. */typedef enum { BSC, AWGN, AWLN } channel_type;extern channel_type channel;	/* Type of channel */extern double error_prob;	/* Error probability for BSC */extern double std_dev;		/* Noise standard deviation for AWGN */extern double lwidth;		/* Width of noise distributoin for AWLN *//* PROCEDURES TO DO WITH CHANNELS. */int  channel_parse (char **, int);void channel_usage (void);