@c "cmd/why.texi"
@c extracted from "../../src/sim/prsim/Command-prsim.cc"
@c by "$(top_srcdir)/scripts/extract_texinfo.awk".

@deffn Command why node [val]
@deffnx Command why-verbose node [val]
@deffnx Command why-1 node [val]
@deffnx Command why-1-verbose node [val]
@deffnx Command why-N node maxdepth [val]
@deffnx Command why-N-verbose node maxdepth [val]
Print reason for node being driven to a given value, 0 or 1.
X is not a valid value for this procedure.  
If @var{val} is not given, it is assumed to be the current value of the node.  
The algorithm examines each node's fanins and follows
nodes on paths where the subexpression is true 
(path through transistors is on).  
The analysis will terminate at state-holding nodes that are not being
driven to their current value.
This is an excellent aid in debugging unexpected values.  
The verbose variant prints expression types as it auto-indents, 
which is more informative but may appear more cluttered.  
The @option{-1} variant only queries through depth 1, 
and the @option{-N} variant queries to a maximum depth of @var{maxdepth}.  
@end deffn

