SPSS® 12.0 Command Syntax Reference

940 MATRIX—END MATRIX
• A logical expression on the IF clause of the END LOOP statement is evaluated as true.
• A BREAK statement is executed within the loop structure (but outside of any nested loop
structures).
Index Clause on the LOOP Statement
An index clause on a LOOP statement creates an index variable whose name is specified immediately
after the keyword LOOP. The variable is assigned an initial value of n. Each time
through the loop, the variable is tested against the terminal value m and incremented by the
increment value k if k is specified, or by 1 if k is not specified. When the index variable is
greater than m for positive increments or less than m for negative increments, control passes
to the statement after the END LOOP statement.
• Both the index clause and the IF clause are optional. If both are present, the index clause
must appear first.
• The index variable must be scalar with a valid matrix variable name.
• The initial value, n, the terminal value, m, and the increment, k (if present), must be scalars
or matrix expressions evaluating to scalars. Non-integer values are truncated to integers
before use.
• If the keyword BY and the increment k are absent, an increment of 1 is used.
IF Clause on the LOOP Statement
The logical expression is evaluated before each iteration of the loop structure. If it is false,
the loop terminates and control passes to the statement after END LOOP.
• The IF clause is optional. If both the index clause and the IF clause are present, the index
clause must appear first.
• As in the DO IF structure, the logical expression of the IF clause is evaluated as scalar, with
positive values being treated as true and 0 or negative values, as false.
IF Clause on the END LOOP Statement
When an IF clause is present on an END LOOP statement, the logical expression is evaluated
after each iteration of the loop structure. If it is true, the loop terminates and control passes
to the statement following the END LOOP statement.
• The IF clause is optional.
• As in the LOOP statement, the logical expression of the IF clause is evaluated as scalar, with
positive values being treated as true and 0 or negative values, as false.
BREAK Statement
The BREAK statement within a loop structure transfers control immediately to the statement
following the (next) END LOOP statement. It is normally placed within a DO IF structure
inside the LOOP structure to exit the loop when specified conditions are met.