HOC(1)							      General Commands Manual							    HOC(1)

NAME

       hoc - interactive floating point language

SYNOPSIS

       hoc [ file ...  ]

DESCRIPTION

       Hoc interprets a simple language for floating point arithmetic, at about the level of BASIC, with C-like syntax and functions.

       The named files are read and interpreted in order.  If no file is given or if file is hoc interprets the standard input.

       Hoc  input consists of expressions and statements.  Expressions are evaluated and their results printed.  Statements, typically assignments
       and function or procedure definitions, produce no output unless they explicitly call print.

       Variable names have 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.

       Expressions are formed with these C-like operators, listed by decreasing precedence.

       ^      exponentiation

       ! - ++ --

       * / %

       + -

       > >= < <= == !=

       &&

       ||

       = += -= *= /= %=

       Built in functions are abs, acos, asin, atan (one argument), cos, cosh, exp, int, log, log10, sin, sinh, sqrt, tan, and tanh.  The function
       read(x) reads a value into the variable x and returns 0 at EOF; the statement print prints a list of expressions that  may  include  string
       constants such as "hello
".

       Control	flow statements are if-else, while, and for, with braces for grouping.	Newline ends a statement.  Backslash-newline is equivalent
       to a space.

       Functions and procedures are introduced by the words func and proc; return is used to return with a value from a function.  Within a  func-
       tion or procedure, arguments are referred to as $1, $2, etc.; all other variables are global.

EXAMPLES

       func gcd() {
	    temp = abs($1) % abs($2)
	    if(temp == 0) return abs($2)
	    return gcd($2, temp)
       }
       for(i=1; i<12; i++) print gcd(i,12)

SOURCE

       /sys/src/cmd/hoc

SEE ALSO

       bc(1), dc(1)
       B. W. Kernighan and R. Pike, The Unix Programming Environment, Prentice-Hall, 1984

BUGS

       Error recovery is imperfect within function and procedure definitions.

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