BAS (I) 1/15/73 BAS (I) NAME bas -- basic SYNOPSISbas[ file ] DESCRIPTIONbasis a dialect of basic [1]. If a file argu- ment is provided, the file is used for input be- fore the console is read.basaccepts 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. Statements have the following syntax: expression The expression is executed for its side ef- fects (assignment or function call) or for printing as described above.doneReturn to system level.drawexpression expression expression A line is drawn on the Tektronix 611 dis- play (/dev/vt0) from the current display position to the XY co-ordinates specified by the first two expressions. (The scale is zero to one in both X and Y directions) If the third expression is zero, the line is invisible. The current display position is set to the end point.displaylist The list of expressions and strings is con- catenated and displayed (i.e. printed) on the 611 starting at the current display po- sition. The current display position is not changed.eraseThe 611 screen is erased.forname=expression expression statementforname=expression expression ...nextTheforstatement repetitively executes a statement (first form) or a group of state- ments (second form) under control of a named variable. The variable takes on the value of the first expression, then is in- cremented by one on each loop, not to ex- ceed the value of the second expression.gotoexpression The expression is evaluated, truncated to an integer and execution goes to the corre- sponding integer numbered statment. If ex- ecuted from immediate mode, the internal statements are compiled first.ifexpression statement The statement is executed if the expression evaluates to non-zero.list[expression [expression]]listis used to print out the stored inter- nal 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 arguments are 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.runThe internal statements are compiled. The symbol table is re-initialized. The random number generator is re-set. Control is passed to the lowest numbered internal statement. Expressions have the following syntax: name A name is used to specify a variable. Names are composed of a letter ('a' - 'z') 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 composed of digits, at most one decimal point ('.') and possibly a scale factor of the formedigits ore-digits.(expression)Parentheses are used to alter normal order of evaluation. expression operator expression Common functions of two arguments are ab- breviated by the two arguments separated by an operator denoting the function. A com- plete list of operators is given below. expression([expression [,expression ...]])Functions of an arbitrary number of argu- ments can be called by an expression fol- lowed by the arguments in parentheses sepa- rated by commas. The expression evaluates to the line number of the entry of the function in the internally stored state- ments. This causes the internal statements to be compiled. If the expression evalu- ates negative, a builtin function is called. The list of builtin functions ap- pears 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. Assign- ment binds right to left, all other opera- tors bind left to right. & |&(logical and) has result zero if either of its arguments are zero. It has result one if both its arguments are non-zero.|(logical 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 Arg(i) is the value of theith actual pa- rameter on the current level of function call. exp Exp(x) is the exponential function of x. log Log(x) is the logarithm base e of x. sin Sin(x) is the sine of x (radians). cos Cos(x) is the cosine of x (radians). atn Atn(x) is the arctangent of x. rnd Rnd() is a uniformly distributed random number between zero and one. expr 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. int Int(x) returns x truncated to an integer. FILES /tmp/btm? temporary SEE ALSO [1] DEC-11-AJPB-D DIAGNOSTICS Syntax errors cause the incorrect line to be typed with an underscore where the parse failed. All other diagnostics are self explanatory. BUGS --