IF_THEN - Conditional execution of operations (Scripting operation)

PURPOSE

Allow conditional execution of sections of the SPIDER operation stream, depending on the logical value of an expression. Modeled after the FORTRAN 'IF...ELSEIF...ELSE...ENDIF'.

SEE ALSO

ELSEIF_THEN	[Conditional execution of operations (Scripting operation)]
ELSE	[Conditional execution of operations (Scripting operation)]
IF	[Conditional expression execution (Scripting operation)]
IF_GOTO	[Conditional jump (Scripting operation)]

USAGE

.OPERATION: IF(<EXP>.<LC>.<EXP>) THEN

~~~~~~~

~~~~~~~

ENDIF

Where:

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

EQ equal

NE not equal

GT greater

GE greater/equal

LT less

LE less/equal

EXAMPLES:

IF([ysize].GE.15) THEN

AC

input001

output001

ENDIF

IF([ysize].LT.15) THEN

AC

input001

output001

ELSEIF ([ysize].LT.150) THEN

AC

input001

output002

ELSE

AC

input001

output003

ENDIF

NOTES

1. Nesting of IF_THEN..ELSE...ENDIF is limited to MAXPRC levels. See: CMLIMIT.INC for current value of MAXPRC.

2. For every 'IF_THEN' there must be a closing ENDIF!

3. There is no '.AND.' comparator.

4. The operation 'ELSEIF' was not available prior to SPIDER release 15.0.

5. Implemented by: ArDean Leith

SUBROUTINES

LOGIFQ

CALLER

SPIDER