Use the while keyword to conditionally iterate a statement. The syntax of the while statement is:

while expression
  statements
wend

statements are executed repeatedly as long as expression evaluates true. The test takes place before statements are executed. Thus, if expression evaluates false on the first pass, the loop does not execute.

Here is an example of calculating scalar product of two vectors, using the while statement:

s = 0
i = 0
while i < n
  s = s + a[i] * b[i]
  i = i + 1
wend

Probably the easiest way to create an endless loop is to use the statement:

while TRUE
  ' ...
wend

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