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For

  • For[ start , test , incr , body ] executes start, then repeatedly evaluates body and incr until test fails to give True.
  • For evaluates its arguments in a non-standard way.
  • For[ start , test , incr ] does the loop with a null body.
  • The sequence of evaluation is test, body, incr. The For exits as soon as test fails.
  • If Break[ ] is generated in the evaluation of body, the For loop exits.
  • Continue[ ] exits the evaluation of body, and continues the loop by evaluating incr.
  • Unless Return[ expr ] or Throw[ expr ] is generated, the final value returned by For is Null.
  • Example: For[tot=0; i=0, i < 3, i++, tot += f[i]]. Note that the roles of semicolon and comma are reversed relative to the C programming language.
  • See the Mathematica book: Section 2.5.9.
  • See also: Do, While, Throw.

    Further Examples

    Here is a common form of a For loop. i++ increments the value of i each time through the loop.

    In[1]:=

    1

    2

    3

    4

    Here is a more complicated For loop. The loop terminates as soon as the test i^2 < 10 fails.

    In[2]:=

    1 + x

    3 + x

    6 + x