Mathematica "Insert" not working

Asked Apr 09 '14 at 21:05

Active Apr 09 '14 at 21:05

Viewed 34 times

Why doesn't this work:

mergeList[a_, b_] := (
  list = a;
  Insert[list, 98, 3];
  Do[
   Do[
    (
     If[
      b[[f]] < list[[s]],
      (Insert[list, b[[f]], s]; Break[])
      ]
     ),
    {s, Length[list]}
    ],
   {f, Length[b]}
   ];
  list
  )

It doesn't give an error, it just outputs the original value of list = a

For example:

mergeList[{1, 2, 3, 4}, {2, 3, 4, 5}]

outputs {1, 2, 3, 4}, and I don't know why.

asked Apr 09 '14 at 21:05

kukac67

1

list = Insert[list, b[[f]], s] – ciao Apr 09 '14 at 21:10
wow... I was thinking it would manipulate the list variable automatically. Thanks – kukac67 Apr 09 '14 at 21:13
1

A common error. Mathematica functions almost never change things given as arguments (they're 'unmutable'). Some notable exceptions are Set, AppendTo and PrependTo, Increment and AddTo. You can think of it as working on a copy. If you want the result to overwrite the original you have to use Set. – Sjoerd C. de Vries Apr 09 '14 at 21:24
More specifically, this answer. – Szabolcs Apr 09 '14 at 22:10
@SjoerdC.deVries Should I remove this question? It was answered only in the comments, and its sort of a duplicate. – kukac67 Apr 10 '14 at 00:16

Mathematica "Insert" not working

0 Answers0