Assignment (Selective Modified) {R}←(EXP X)f←Y

f may be any dyadic function which returns an explicit result. Y may be any array whose items are appropriate to function f. X must be the name of an existing array. EXP is an expression that selects elements of X. (See Assignment (Selective) for a list of allowed selection functions.) The selected elements of X must be appropriate to function f.

Y is either an array of the same shape as the selected elements of X or a scalar that is notionally extended to be the same shape as the selection.

The operator loops through the selected elements of X in ravel order. For each selected element X[i], it calculates the result of X[i]fY[i] and assigns it back to the same element X[i].

R is the "pass-through" value, that is, the value of Y. If the result of the derived function is not assigned or used, there is no explicit result.

Example

      A
12 36 23 78 30

      ((A>30)/A) ×← 100
      A
12 3600 23 7800 30

As the operator performs a loop, if an element of X is selected more than once, function f will be applied the corresponding number of times and successively to the same element of X.

      a←3⍴0
      (5⍴a)+←1
      a
2 2 1