MaxI

MaxI[ list ] returns the index of the largest value in a list.

Usages

`MaxI[ list ]`

MaxI[ list ] returns the position (starting at 1) of the element of list with the largest numerical value.

Example	in	out
The largest value is at position `1`.	`MaxI[ {3, 2, 1} ]`	`1`
`Sqrt[7]` is the largest value.	`MaxI[ {Sqrt[3], Sqrt[5], Sqrt[7]} ]`	`3`
Use the index to look up the element.	`L := {40, 10, 30} i := MaxI[L] v := L[[i]]`	`i = 1` `v = 40`

Details

Equal values: if the largest value occurs more than once, the first position is returned: MaxI[ {5, 2, 5} ] returns 1.
Elements without a numerical value: if any element has no numerical value (such as x), MaxI is left unevaluated: MaxI[ {2, x} ] stays MaxI[ {2, x} ].

Invalid input	Result
`MaxI[ {} ]`	`0`, which is not a valid position.
`MaxI[ 5 ]`	`5`: an argument that is not a list is returned unchanged.
`MaxI[ 3, 5 ]`	Error: the number of arguments should be 1

Warning

MaxI only works correctly if the largest value is greater than 0. If all values are 0 or negative, MaxI returns 0: MaxI[ {-3, -1, -2} ] returns 0 instead of 2. In that case, use MinI on the negated values, for example MinI[ Map[x -> CalcTimes[-1, x], L] ].

See also: Max, MinI, SortI, FindI