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138 Appendix A6 OxGauss Language Reference

The do while statement excutes the statement-list as long as the test expression is

nonzero (for a matrix: at least one element is nonzero). The test is performed before

the statement-list is executed. Note that endo has only one d.

The do until statement excutes the statement-list as long as the test expression is

nonzero (for a matrix: at least one element is nonzero). The test is performed before

the statement-list is executed. so do until expr corresponds to do while not expr.

The for expression corresponds to:

identiﬁer = init-expr;

do while identiﬁer <= test-expr;

statement-list

identiﬁer = identiﬁer + increment-expr;

endo;

The main feature is that identiﬁer is local to the loop, so cannot be accessed after the

loop is ﬁnished. If another variable with the same name already exists, that variable is

hidden during the loop. The value of test-expr and increment-expr is evaluated when

the loop is entered, and cannot be changed during the loop. If increment-expr is zero,

the loop is not executed; it is allowed to be negative. The values of init-expr, test-expr

and increment-expr are truncated to integers.

A6.7.4 Call statements

Use call to call a function and discard the return values, see §A6.6.3.

A6.7.5 Jump and pop statements

jump-statement:

break ;

continue ;

goto label;

goto label( parameter-list );

gosub label;

gosub label( parameter-list );

return label;

return label( parameter-list );

pop-statement:

pop identiﬁer ;

A continue statement may only appear within an iteration statement and causes

control to pass to the loop-continuationportion of the smallest enclosing iteration state-

ment.

A break statement may only appear within an iteration statement and terminates

the smallest enclosing iteration statement.

The use of goto should be kept to a minimum, but could be useful to jump out of a

nested loop, jump to the end of a routine or when converting Fortran code. It is always

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Matrix Elements VB-800 Manual de usuario Pagina 146