.TH HOC 1
.SH NAME
hoc \- interactive floating point language
.SH SYNOPSIS
.B hoc
[ file ... ]
.SH DESCRIPTION
.I hoc
interprets a simple language for floating point arithmetic,
at about the level of BASIC, with C-like syntax and
functions.
.PP
The named
.IR file s
are read and interpreted in order.
If no
.I file
is given or if
.I file
is `\-'
.I hoc
interprets the standard input.
.PP
.I hoc
input consists of
.I expressions
and
.IR statements .
Expressions are evaluated and their results printed.
Statements, typically assignments and function or procedure
definitions, produce no output unless they explicitly call
.IR print .
.PP
Variable names are the usual syntax, including `_'; the name `_'
by itself contains the value of the last expression evaluated.
The variables E, PI, PHI, GAMMA and DEG are predefined;
the last is 59.25..., degrees per radian.
.PP
Expressions are formed with these operators:
.nf
.ta .5i 1.5i
	^	exponentiation
	! \- ++ \-\-	unary logical and arithmetic negation, ...
	* / %	the obvious
	+ \-	ditto
	> >= < <= == !=
	&&
	\(or\(or
	= += \-= \(**= /= %=
.fi
Built in functions include 
.IR abs ,
.I atan
(one argument),
.IR cos ,
.IR exp ,
.IR int ,
.IR log ,
.IR log10 ,
.IR sin ,
and
.IR sqrt .
The function
.I read(x)
reads a value into the variable 
.IR x ;
the statement
.I print
prints a list of expressions that may include
string constants such as
.IR \&\&\&"hello\en" .
.PP
Control flow includes
.IR if-else ,
.IR while ,
and
.IR for ,
with braces for grouping.
End of line marks end of statement, as does a semicolon.
.PP
Functions and procedures are introduced by the words
.I func
and
.IR proc ;
.I return
is used to return, with a value from a function.
Within a function or procedure,
arguments are referred to as
.IR $1 ,
.IR $2 ,
etc.; all other variables are global.
.SH "SEE ALSO"
.I
The Unix Programming Environment
by Brian Kernighan and Rob Pike.
.br
bc(1),
dc(1)
.SH BUGS
Error recovery is imperfect within function and procedure definitions.
.br
The treatment of newlines is not exactly user-friendly.