Chapter 19
ICL

19.1 Syntax

This section gives a summary of the ICL language syntax. Square brackets imply that the enclosed part of the construct is optional.

Operational Mode

—

Direct:

Statements are executed as they are entered.

Procedure:

Statements are first entered into a procedure, then the procedure is executed.

Data types —

Real

Integer

Logical

String

Expression—

    value [operator value operator value ...]

Value—

Constant:

Real

-        1.234E-5,  3.14159

Integer

-     123,  %B100110,  %O377,  %Xffff

Logical

-     TRUE,  FALSE

String

-      ’This is a string’,  "So is this"

Variable:

Name

- Letter followed by letters, digits, or underscores (15 significant)

Function:

See below.

Operator—

1	**
2	*  /
3	+  -
4	=  >  <  >=  <=  <>  :
5	NOT  AND  OR  &

&

performs string concatenation.

:

is formatting operator (X:n:m is X converted to an n character string with m decimal places).

Statement—

Normally one statement per line. A tilde (~) at the end of a line indicates that the statement continues on the next line.

Direct Statement:

These statements can be used in any operational mode.

Comment

-

Any line starting with the characters ‘{’ or ‘;’.

Immediate Statement

-

= expression (prints value of expression)

Assignment Statement

-

variable = expression (assignment to variable)

Command

-

command_name p1 p2 …(command or procedure call)

In commands or procedure calls, parameters are separated by a comma or spaces. Expressions or variables should be enclosed in parentheses.

Control Statement:

These statements can only be used in the Procedure operational mode.

IF Statement

-

    IF expression  
      statements  
    [ELSE IF expression  
      statements]  
    [ELSE  
      statements]  
    END IF

LOOP Statement

-

    LOOP  
      statements  
    END LOOP  
 
    [LOOP] FOR var = exp1 TO exp2 [STEP exp3]  
      statements  
    END LOOP  
 
    [LOOP] WHILE expression  
      statements  
    END LOOP

You can escape from a loop via a BREAK statement.

PROCEDURE Statement

-

    [HIDDEN] PROC name p1 p2 ....  
      statements  
    END PROC

EXCEPTION Statement

-

    EXCEPTION name  
      statements  
    END EXCEPTION

Command Search Path—

(1)

User defined commands (defined by DEFSTRING, DEFUSER, DEFPROC)

(2)

User written procedures (defined by PROC)

(3)

ICL commands to control ADAM tasks (ALOAD, etc)

(4)

ADAM commands (defined by DEFINE)

(5)

Other ICL built-in commands (see below)

19.2 Commands

The commands which are likely to be of most use in data analysis are classified below. Commands relevant mainly to data acquisition are omitted. A full list is contained in SG/5.

Information & Escape—

HELP:

Display on-line documentation.

EXIT:

Exit from ICL.

Defining user commands—

DEFSTRING:

Associate a command with an equivalence string.

DEFINE:

Define a command to run an ADAM task.

DEFUSER:

Associate a command with a user written subroutine.

DEFPROC:

Associate a command with a procedure.

I/O—

Terminal I/O:

PRINT:

Output to the terminal.

INPUT:

Input a string.

INPUTI:

Input integers.

INPUTL:

Input logical values.

INPUTR:

Input real numbers.

Screen mode:

SET SCREEN:

Set screen I/O mode.

SET NOSCREEN:

Set normal I/O mode.

SET ATTRIBUTES:

Set attributes for text written with the LOCATE command.

LOCATE:

Write to screen at specified position.

CLEAR:

Clear lines in a specified range.

Keyboard facilities:

KEY:

Define an equivalence string for a key.

KEYTRAP:

Specify trapping of a key.

KEYOFF:

Turn off trapping of a key.

File I/O:

CREATE:

Create a file and open it for output.

OPEN:

Open an existing file for input.

APPEND:

Open an existing file for appending.

CLOSE:

Close a file opened with CREATE, OPEN, or APPEND.

WRITE:

Write to a file.

READ:

Read a string from a file.

READI:

Read integers from a file.

READL:

Read logical values from a file.

READR:

Read real numbers from a file.

Access to DCL—

General:

$:

Issue a DCL command.

SPAWN:

Spawn a subprocess to issue one or more DCL commands.

DEFAULT:

Set/Show default directory.

Managing tape drives:

ALLOC:

Allocate a device.

DEALLOC:

Deallocate a device.

MOUNT:

Mount a tape.

DISMOUNT:

Dismount a tape.

Parameters—

SETPAR:

Set the value of a parameter where the program has an associated command.

GETPAR:

Get the value of a parameter where the program has an associated command.

CREATEGLOBAL:

Create a global parameter.

SETGLOBAL:

Set the value of a global parameter.

GETGLOBAL:

Get the value of a global parameter into an ICL variable.

Procedures—

Listing and editing:

LIST:

List a procedure.

PROCS:

List procedure names.

VARS:

List procedure variables.

EDIT:

Edit a procedure.

SET EDITOR:

Change the editor (TPU, EDT, or LSE) used by EDIT.

Saving and loading:

SAVE:

Save a procedure.

LOAD:

Accept commands from a saved procedure.

DELETE:

Delete a procedure.

Tracing execution:

SET TRACE:

Switch tracing of procedures ON.

SET NOTRACE:

Switch tracing of procedures OFF.

Errors and Exceptions—

SIGNAL:

Signal an ICL exception.

Help system—

DEFHELP:

Define the source of help information.

Miscellaneous—

TASKS:

List all loaded tasks.

SAVEINPUT:

Save previous input lines in a text file.

SETPRECISION:

Set the number of decimal digits precision for unformatted conversions of real values to strings.

19.3 Functions

The following functions are available for use in expressions (N.B. The ‘$\ast$’ symbol in the Type column stands for ‘Real or Integer’).

Mathematical Functions—

Name	Type	Definition
SIN(X)	Real	Trig. functions (x in radians).
COS(X)	Real
TAN(X)	Real
SIND(X)	Real	Trig. functions (x in degrees).
COSD(X)	Real
TAND(X)	Real
ASIN(X)	Real	${sin}^{-1}xwhere-1\le x\le 1$; $-\pi /2\le result\le \pi /2$.
ACOS(X)	Real	${cos}^{-1}xwhere-1\le x\le 1$; $0\le result\le \pi$.
ATAN(X)	Real	${tan}^{-1}x$; $-\pi /2\le result\le \pi /2$.
ATAN2(X1,X2)	Real	${tan}^{-1}\left(x_1/x_2\right)$; $-\pi <result\le \pi$.
ASIND(X)	Real	Inverse trig functions in degrees.
ACOSD(X)	Real
ATAND(X)	Real
ATAN2D(X1/X2)	Real
SINH(X)	Real	Hyperbolic functions.
COSH(X)	Real
TANH(X)	Real
ABS(X)	*	$\mid x\mid$.
DIM(X1,X2)	*	Positive difference between $x_1$ and $x_2$.
EXP(X)	Real	$e^x$.
LOG(X)	Real	$lnx$.
LOG10(X)	Real	${log}_{10}x$.
MIN(X1,X2,...)	*	Minimum of two or more arguments.
MAX(X1,X2,...)	*	Maximum of two or more arguments.
MOD(X1,X2)	*	Remainder when $x_1$ is divided by $x_2$.
SIGN(X1,X2)	*	Transfer of sign $\mid x_1\mid$ Sign $x_2$.
SQRT(X)	Real	$\sqrt{x}$.

Formatting and String Handling Functions—

BIN(I,n,m)	String	Integer I formatted in binary into an n char string
		with m significant digits.
DEC(I,n,m)	String	Integer I formatted in decimal into an n char string
		with m significant digits.
HEX(I,n.m)	String	Integer I formatted in hexadecimal into an n char string
		with m significant digits.
OCT(I,n,m)	String	Integer I formatted in octal into an n char string
		with m significant digits.
DECL(S)	Real	Declination in radians from string in degrees, minutes, seconds.
DEC2S(R,NDP,SEP)	String	String in DMS with separator SEP and NDP decimal places
		on seconds, from Dec in radians.
RA(S)	Real	Right Ascension in radians from a string in hours, minutes, seconds.
RA2S(R,NDP,SEP)	String	String in HMS with separator SEP and NDP decimal places
		on seconds, from RA in radians.
CHAR(I)	String	Character with ASCII value I.
ICHAR(S)	Integer	ASCII value of first character of string S.
INDEX(S1,S2)	Integer	Position of first occurrence of string S2 in string S1.
LEN(S)	Integer	Length of string.
ELEMENT(I,DELIM,S)	String	Ith element of delimited string.
SUBSTR(S,n,m)	String	Substring of S beginning at n of length m.
SNAME(S,n,m)	String	Name derived by concatenating string S with integer n
		formatted into m characters including leading zeros.
UPCASE(S)	String	String S converted to upper case.
LGE(S1,S2)	Logical	True if S1 $\ge$ S2 (ASCII collating sequence).
LGT(S1,S2)	Logical	True if S1 $>$ S2 (ASCII collating sequence).
LLE(S1,S2)	Logical	True if S1 $\le$ S2 (ASCII collating sequence).
LLT(S1,S2)	Logical	True if S1 $<$ S2 (ASCII collating sequence).

Bitwise Logical Operations—

IAND(I1,I2)	Integer	Bitwise AND.
IOR(I1,I2)	Integer	Bitwise OR.
IEOR(I1,I2)	Integer	Bitwise Exclusive OR.
INOT(I)	Integer	Bitwise Complement.

Type Conversion and Inquiry Functions—

FLOAT(I)	Real	Integer I converted to real.
IFIX(X)	Integer	X converted to integer by truncation.
INT(X)	Integer	X converted to integer by truncation.
NINT(X)	Integer	Nearest integer to X.
INTEGER(X)	Integer	X converted to integer.
LOGICAL(X)	Logical	X converted to logical.
REAL(X)	Real	X converted to real.
STRING(X)	String	X converted to string.
TYPE(X)	String	The type of X (‘REAL’, ‘INTEGER’, ‘LOGICAL’,
		‘STRING’, or ‘UNDEFINED’).
UNDEFINED(X)	Logical	TRUE if X is undefined.

Miscellaneous Functions—

DATE()	String	Current date.
TIME()	String	Current time.
GETNBS(S)	Any	Value of noticeboard item.
GET_SYMBOL(S)	String	Value of DCL symbol.
INKEY()	Integer	Key value of last key trapped (Screen mode only).
KEYVALS(S)	Integer	Value of key with name S.
OK(stat)	Logical	True if VMS Status OK.
FILE_EXISTS(S)	Logical	True if file S exists.
RANDOM(I)	Real	Random number between 0 and 1 from seed variable I.
VARIABLE(proc,X)	Any	Returns value of variable X of procedure proc.

19.4 Exceptions