It is sometimes convenient to assign to an array values which are functions of the array indices. This can be done using ``implicit loops'', such as
DEFINE REAL A[10,10] LET A[I,J] = EXP(-((I-5)|2)**2-((J-6)|3)**2)in which I and J have NOT been declared as known variables. I and J are known as ``implicit variables''. The preceding expression is equivalent to the following commands
DEFINE REAL A[10,10] FOR J 1 TO 10 FOR I 1 TO 10 LET A[I,J] = EXP(-((I-5)|2)**2-((J-6)|3)**2) NEXT NEXTbut it executes thousands of times faster... Mixing of implicit and declared (or loop) variables is strictly forbidden at present. It can usually be avoided by using intermediate arrays.