5 added 3 characters in body
source | link

Jelly, 7 bytes

ṚZ$3СS

Try it online!

Saved 1 byte thanks to Erik the Outgolfer (also thanks to a suggestion for fixing a bug).

How?

ṚZ$3СS || Full program (monadic).

   3С  || Do this 3 times and collect results in a list
  $     || >–> Apply the last two links as a monad
Ṛ       || ||>–––> Reverse,
 Z      || ||>–––> Transpose.
      S || Summation.

Jelly, 7 bytes

ṚZ$3СS

Try it online!

Saved 1 byte thanks to Erik the Outgolfer (also thanks to a suggestion for fixing a bug).

How?

ṚZ$3СS || Full program (monadic).

   3С  || Do this 3 times and collect results in a list
  $     || > Apply the last two links as a monad
Ṛ       || ||> Reverse,
 Z      || ||> Transpose.
      S || Summation.

Jelly, 7 bytes

ṚZ$3СS

Try it online!

Saved 1 byte thanks to Erik the Outgolfer (also thanks to a suggestion for fixing a bug).

How?

ṚZ$3СS || Full program (monadic).

   3С  || Do this 3 times and collect results in a list
  $     || –> Apply the last two links as a monad
Ṛ       || –––> Reverse,
 Z      || –––> Transpose.
      S || Summation.
4 deleted 9 characters in body
source | link

Jelly, 7 bytes

ṚZ$3СS

Try it online!

Saved 1 byte thanks to Erik the Outgolfer (also thanks to a suggestion for fixing a bug).

How?

ṚZ$3СS || Full program (monadic).

   3С  || Do this 3 times and collect results in a list...
  $     || > Apply the last two links as a monad:
Ṛ       || ...||> Reverse, then...
 Z      || ...||> Transpose.
      S || Summation.

Jelly, 7 bytes

ṚZ$3СS

Try it online!

Saved 1 byte thanks to Erik the Outgolfer (also thanks to a suggestion for fixing a bug).

How?

ṚZ$3СS || Full program (monadic).

   3С  || Do this 3 times and collect results in a list...
  $     || Apply the last two links as a monad:
Ṛ       || ... Reverse, then...
 Z      || ... Transpose
      S || Summation.

Jelly, 7 bytes

ṚZ$3СS

Try it online!

Saved 1 byte thanks to Erik the Outgolfer (also thanks to a suggestion for fixing a bug).

How?

ṚZ$3СS || Full program (monadic).

   3С  || Do this 3 times and collect results in a list
  $     || > Apply the last two links as a monad
Ṛ       || ||> Reverse,
 Z      || ||> Transpose.
      S || Summation.
3 deleted 48 characters in body
source | link

Jelly, 7 bytes

ṚZ$3СS

Invalid... Fixed point can occur earlier..Try it online!

Saved 1 byte thanks to Erik the Outgolfer (also thanks to a suggestion for fixing a bug).

How?


ṚZ$3СS || Full program (monadic).

   3С  || Do this 3 times and collect results in a list...
  $     || Apply the last two links as a monad:
Ṛ       || ... Reverse, then...
 Z      || ... Transpose
      S || Summation.

Invalid... Fixed point can occur earlier...

Jelly, 7 bytes

ṚZ$3СS

Try it online!

Saved 1 byte thanks to Erik the Outgolfer (also thanks to a suggestion for fixing a bug).

How?


ṚZ$3СS || Full program (monadic).

   3С  || Do this 3 times and collect results in a list...
  $     || Apply the last two links as a monad:
Ṛ       || ... Reverse, then...
 Z      || ... Transpose
      S || Summation.
    Post Undeleted by Mr. Xcoder
    Post Deleted by Mr. Xcoder
2 added 102 characters in body
source | link
1
source | link