BAS(1)							      General Commands Manual							    BAS(1)

NAME

       bas - basic

SYNOPSIS

       bas [ file ]

DESCRIPTION

       Bas  is	a dialect of Basic.  If a file argument is provided, the file is used for input before the terminal is read.  Bas accepts lines of
       the form:

	  statement
	  integer statement

       Integer numbered statements (known as internal statements) are stored for later execution.  They are  stored  in  sorted  ascending  order.
       Non-numbered  statements  are immediately executed.  The result of an immediate expression statement (that does not have `=' as its highest
       operator) is printed.  Interrupts suspend computation.

       Statements have the following syntax:

       expression
	    The expression is executed for its side effects (assignment or function call) or for printing as described above.

       comment
	    This statement is ignored.	It is used to interject commentary in a program.

       done
	    Return to system level.

       dump
	    The name and current value of every variable is printed.

       edit
	    The UNIX editor, ed, is invoked with the file argument.  After the editor exits, this file is recompiled.

       for name = expression expression statement
       for name = expression expression
       next
	    The for statement repetitively executes a statement (first form) or a group of statements (second form) under control of a named vari-
	    able.   The  variable  takes on the value of the first expression, then is incremented by one on each loop, not to exceed the value of
	    the second expression.

       goto expression
	    The expression is evaluated, truncated to an integer and execution goes to the corresponding integer numbered statment.   If  executed
	    from immediate mode, the internal statements are compiled first.

       if expression statement
       if expression
       [ else
       fi
	    The  statement  (first  form) or group of statements (second form) is executed if the expression evaluates to non-zero.  In the second
	    form, an optional else allows for a group of statements to be executed when the first group is not.

       list [expression [expression]]
	    is used to print out the stored internal statements.  If no arguments are given, all internal statements are printed.  If one argument
	    is	given,	only that internal statement is listed.  If two arguments are given, all internal statements inclusively between the argu-
	    ments are printed.

       print list
	    The list of expressions and strings are concatenated and printed.  (A string is delimited by " characters.)

       prompt list
	    Prompt is the same as print except that no newline character is printed.

       return [expression]
	    The expression is evaluated and the result is passed back as the value of a function  call.   If  no  expression  is  given,  zero	is
	    returned.

       run
	    The  internal  statements are compiled.  The symbol table is re-initialized.  The random number generator is reset.  Control is passed
	    to the lowest numbered internal statement.

       save [expression [expression]]
	    Save is like list except that the output is written on the file argument.  If no argument is given on the command, b.out is used.

       Expressions have the following syntax:

       name
	    A name is used to specify a variable.  Names are composed of a letter followed by letters and digits.  The first four characters of  a
	    name are significant.

       number
	    A number is used to represent a constant value.  A number is written in Fortran style, and contains digits, an optional decimal point,
	    and possibly a scale factor consisting of an e followed by a possibly signed exponent.

       ( expression )
	    Parentheses are used to alter normal order of evaluation.

       _ expression
	    The result is the negation of the expression.

       expression operator expression
	    Common functions of two arguments are abbreviated by the two arguments separated by an operator denoting  the  function.   A  complete
	    list of operators is given below.

       expression ( [expression [ , expression] ... ] )
	    Functions  of  an  arbitrary  number of arguments can be called by an expression followed by the arguments in parentheses separated by
	    commas.  The expression evaluates to the line number of the entry of the function in the internally stored	statements.   This  causes
	    the  internal  statements  to  be  compiled.  If the expression evaluates negative, a builtin function is called.  The list of builtin
	    functions appears below.

       name [ expression [ , expression ] ...  ]
	    Each expression is truncated to an integer and used as a specifier for the name.  The result is syntactically  identical  to  a  name.
	    a[1,2] is the same as a[1][2].  The truncated expressions are restricted to values between 0 and 32767.

       The following is the list of operators:

       =      =  is  the  assignment operator.	The left operand must be a name or an array element.  The result is the right operand.	Assignment
	      binds right to left,

       &  |   & (logical and) has result zero if either of its arguments are zero.  It has result one if both its arguments are non-zero.  | (log-
	      ical or) has result zero if both of its arguments are zero.  It has result one if either of its arguments are non-zero.

       <  <=  >  >=  ==  <>
	      The  relational  operators  (< less than, <= less than or equal, > greater than, >= greater than or equal, == equal to, <> not equal
	      to) return one if their arguments are in the specified relation.	They return zero otherwise.   Relational  operators  at  the  same
	      level extend as follows: a>b>c is the same as a>b&b>c.

       + -    Add and subtract.

       * /    Multiply and divide.

       ^      Exponentiation.

       The following is a list of builtin functions:

       arg(i) is the value of the i -th actual parameter on the current level of function call.

       exp(x) is the exponential function of x.

       log(x) is the natural logarithm of x.

       sqr(x) is the square root of x.

       sin(x) is the sine of x (radians).

       cos(x) is the cosine of x (radians).

       atn(x) is the arctangent of x.  Its value is between -n/2 and n/2.

       rnd( ) is a uniformly distributed random number between zero and one.

       expr( )
	      is the only form of program input.  A line is read from the input and evaluated as an expression.  The resultant value is returned.

       abs(x) is the absolute value of x.

       int(x) returns x truncated (towards 0) to an integer.

FILES

       /tmp/btm? temporary
       b.out	      save file
       /bin/ed	 for edit

DIAGNOSTICS

       Syntax errors cause the incorrect line to be typed with an underscore where the parse failed.  All other diagnostics are self explanatory.

BUGS

       Has been known to give core images.
       Catches interrupts even when they are turned off.

																	    BAS(1)