Post Closed as "Duplicate" by MarcoB, Kuba, user9660, Michael E2, Mr.Wizard

occurred Feb 1, 2016 at 5:47

added 53 characters in body

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edited Jan 20, 2016 at 14:19

As you can see,the original Differences will get {} when your parameter is a list with one element just.

Differences /@ {{1, 2, 3}, {4, 5}, {6}}

{{1, 1}, {1}, {}}

Then we can change it like this

Unprotect[Differences];
Differences[{a_}] := {a};
Differences /@ {{1, 2, 3}, {4, 5}, {6}}

{{1, 1}, {1}, {6}}

But the same method don't fit the Times and Divide

Unprotect[Times];
Times[0, 0] := "NAN"
Times[0, 0]
0*0
Times[2, 3]

Or like the Divide

Unprotect[Divide];
Divide[0, 0] := "NAN"
Divide[0, 0]
0/0
Divide[2, 3]

As you can see,the original Differences will get {}

Differences /@ {{1, 2, 3}, {4, 5}, {6}}

{{1, 1}, {1}, {}}

Then we can change it like this

Unprotect[Differences];
Differences[{a_}] := {a};
Differences /@ {{1, 2, 3}, {4, 5}, {6}}

{{1, 1}, {1}, {6}}

But the same method don't fit the Times and Divide

Unprotect[Times];
Times[0, 0] := "NAN"
Times[0, 0]
0*0
Times[2, 3]

Or like the Divide

Unprotect[Divide];
Divide[0, 0] := "NAN"
Divide[0, 0]
0/0
Divide[2, 3]

As you can see,the original Differences will get {} when your parameter is a list with one element just.

Differences /@ {{1, 2, 3}, {4, 5}, {6}}

{{1, 1}, {1}, {}}

Then we can change it like this

Unprotect[Differences];
Differences[{a_}] := {a};
Differences /@ {{1, 2, 3}, {4, 5}, {6}}

{{1, 1}, {1}, {6}}

But the same method don't fit the Times and Divide

Unprotect[Times];
Times[0, 0] := "NAN"
Times[0, 0]
0*0
Times[2, 3]

Or like the Divide

Unprotect[Divide];
Divide[0, 0] := "NAN"
Divide[0, 0]
0/0
Divide[2, 3]

Source Link

asked Jan 20, 2016 at 13:56

How to change the built-in function?

As you can see,the original Differences will get {}

Differences /@ {{1, 2, 3}, {4, 5}, {6}}

{{1, 1}, {1}, {}}

Then we can change it like this

Unprotect[Differences];
Differences[{a_}] := {a};
Differences /@ {{1, 2, 3}, {4, 5}, {6}}

{{1, 1}, {1}, {6}}

But the same method don't fit the Times and Divide

Unprotect[Times];
Times[0, 0] := "NAN"
Times[0, 0]
0*0
Times[2, 3]

Or like the Divide

Unprotect[Divide];
Divide[0, 0] := "NAN"
Divide[0, 0]
0/0
Divide[2, 3]

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