IF - Conditional expression execution (Scripting operation)

PURPOSE

To allow evaluation of a conditional expression or loop iteration control. (Modeled after the FORTRAN 'IF' statement).

SEE ALSO

IF_GOTO	[Conditional jump (Scripting operation)]
IF_THEN	[Conditional execution of operations (Scripting operation)]
DO	[Start of DO loop (Scripting operation)]
EXIT	[Ends execution of current operation loop (Scripting operation)]
CYCLE	[Starts next loop iteration (Scripting operation)]

USAGE

.OPERATION: IF ( <EXP><LC><EXP> ) <R> = <EXP>

    <or>
IF ( <EXP><LC><EXP> ) EXIT
    <or>
IF ( <EXP><LC><EXP> ) CYCLE

Where:

1. <EXP> is an expression
2. <R> is a register variable.
3. <LC> is a logical comparator. The following comparators are allowed:

Comparator	Alternate	Comparision
.EQ.	==	Equal to
.NE.	/=	Not equal to
.GT.	>	Greater than
.GE.	>=	Greater than or equal to
.LT.	<	Less than
.LE.	<=	Less than or equal to

NOTES

1. Examples:

   IF( [xlen] .GE. 15 )	[xpad] = 57
   IF( [xlen] >= 15 )	[xpad] = 57
   IF( [xlen] .LT. (13-2) )	[resol] = 5.6
   IF( [xlen] .LT. 13 )	CYCLE     (Within a DO loop)

SUBROUTINES

LOGIFQ

CALLER

SPIDER