I have been trying to make this code work for two days.
Actually it is a C code which I am trying to implicate to SMath. C code is also included and runs perfectly.
In SMath, code works to a point actually. When I debug it I can see it can assign numbers, backtrack if there is no option.
So SMath code also seems legit but eventually the algorithm just stop working. No error no significant reason.
With different puzzles, code terminated at different places at middle of calculation.
I couldn't figure out what is wrong. Is it a bug or my coding is insufficient?
Any help should be appreciated.

Regards.

sudoku.sm (26 KiB) downloaded 61 time(s).
sudoku.7z (38 KiB) downloaded 32 time(s).

I posted something very inaccurate before and have since deleted it. However, in my testing, it seems that it's not dependent on the number of iterations. The function seems to stop when rw,cl get to around 2,4 or 2,5. This is independent of the number of function calls to fillSudoku.

Wrote

I posted something very inaccurate before and have since deleted it. However, in my testing, it seems that it's not dependent on the number of iterations. The function seems to stop when rw,cl get to around 2,4 or 2,5. This is independent of the number of function calls to fillSudoku.

This looks to correlate to a depth of ~21 or 22 levels of recursion no matter the starting puzzle.

Wrote

With different puzzles, code terminated at different places at middle of calculation.
I couldn't figure out what is wrong. Is it a bug or my coding is insufficient?

I never heard of Sudoku. As it looks, you first scan for coincidence.
Can it relate to some truth table ? Then else game ... !

... your original creates "critical error", that can be repaired in the first module.

Wrote

... your original creates "critical error", that can be repaired in the first module.

Sudoku First Module.sm (17 KiB) downloaded 34 time(s).

... make sure you completely understand the Bolean
from the code you imitate. As corrected, red.
Red may mean not winning ?

sudoku Freak.sm (23 KiB) downloaded 35 time(s).

Wrote

Wrote

I posted something very inaccurate before and have since deleted it. However, in my testing, it seems that it's not dependent on the number of iterations. The function seems to stop when rw,cl get to around 2,4 or 2,5. This is independent of the number of function calls to fillSudoku.

This looks to correlate to a depth of ~21 or 22 levels of recursion no matter the starting puzzle.

To better illustrate what I think is happening I've created the following worksheet. The first function definition is just a simple function that calls itself recursively until its 200th call at which point it exits. However, when run it experiences the same error as we see in the sudoku.sm. I rewrote the function using a try/on error and we see we only get to 50 iterations before it fails.


recursion.sm (4 KiB) downloaded 29 time(s).

Wrote

This looks to correlate to a depth of ~21 or 22 levels of recursion no matter the starting puzzle.

Wrote

To better illustrate what I think is happening I've created the following worksheet. The first function definition is just a simple function that calls itself recursively until its 200th call at which point it exits. However, when run it experiences the same error as we see in the sudoku.sm. I rewrote the function using a try/on error and we see we only get to 50 iterations before it fails.


recursion.sm (4 KiB) downloaded 29 time(s).

What I understood considering your last messages, you think there is nothing significant wrong with the code itself. Problem is SMath handling of recursions.
So, it comes forward that is why I wouldn't be able to make an SMath Sudoku Solver with recursion.

Thank you Alyles.

I think it's possible to fill the '0' positions of the 9x9 Sudoku
with random not common to the existing filled position.
Filling one col at time, collect ...

Wrote

Wrote

This looks to correlate to a depth of ~21 or 22 levels of recursion no matter the starting puzzle.

Wrote

To better illustrate what I think is happening I've created the following worksheet. The first function definition is just a simple function that calls itself recursively until its 200th call at which point it exits. However, when run it experiences the same error as we see in the sudoku.sm. I rewrote the function using a try/on error and we see we only get to 50 iterations before it fails.


recursion.sm (4 KiB) downloaded 29 time(s).

What I understood considering your last messages, you think there is nothing significant wrong with the code itself. Problem is SMath handling of recursions.
So, it comes forward that I wouldn't be able to make an SMath Sudoku Solver.

Thank you Alyles.

I remember this limitation was introduced some time ago to avoid unintentional hard crashes on wrong formed algorithms; considering that any recursive algorithm can be made iterative, you probably have to design it in another way or find a different code

As Davide said, you don't have to do it recursively.

It may be slow, but it works. Might be able to optimize for better performance.


sudoku_lyles2.sm (28 KiB) downloaded 36 time(s).

Wrote

As Davide said, you don't have to do it recursively.

It may be slow, but it works. Might be able to optimize for better performance.


sudoku_lyles2.sm (28 KiB) downloaded 36 time(s).

Well it works for the first two puzzles at least. Having issues with the third. Haven't tried the fourth....

It's a start

Wrote

Well it works for the first two puzzles at least. Having issues with the third. Haven't tried the fourth....

It works for the fourth, but fails for the third puzzle.

Wrote

I remember this limitation was introduced some time ago to avoid unintentional hard crashes on wrong formed algorithms; considering that any recursive algorithm can be made iterative, you probably have to design it in another way or find a different code

Wow, I didn't know there is a purposed limitation for recursion. For those who knows what they are doing, I think that limit can be removed by adding an extra code at the beginning like (recurselimit:=0), or re-adding the limit (recurselimit:=1).

Yeah it can be made iterative, alyles already did one as far as I can see. I just wanted you guys to check if I did something wrong about my algorithm. I just love recursing, I always feel like it is magical to me.

Thank you all guys, regards

Wrote

Wrote

Well it works for the first two puzzles at least. Having issues with the third. Haven't tried the fourth....

It works for the fourth, but fails for the third puzzle.

Don't bother about it. I found these sudoku's on internet without checking them.
I checked that puzzle with C code right now and it has no solution.

Regards

Confirmed: puzzle 3 fails "Requested matrix does not exist" [q=> 1..99]

Wrote

Wow, I didn't know there is a purposed limitation for recursion. For those who knows what they are doing, I think that limit can be removed by adding an extra code at the beginning like (recurselimit:=0), or re-adding the limit (recurselimit:=1).

Hi. It exists in other languages. For instance, can see it at https://reference.wolfram.com/language/ref/$RecursionLimit.html

Best regards.
Alvaro.

Wrote

Don't bother about it. I found these sudoku's on internet without checking them.
I checked that puzzle with C code right now and it has no solution.

You mean puzzle 3 has no solution ?
Solution is => give to champions.
Attached utilities may be useful otherwise.
Mathemtica 4.0 "recursion limit" is pure jargon.
In some program, if/otherwise does not work [if/else = YES].
Is there a catch wrt puzzle 3 ... Watson ?

Utilities Matrix Count in Soduku.sm (22 KiB) downloaded 33 time(s).

Hi. Here, the mathcad 11 version for the recursive method. Notice that mathcad don't pass values by reference, only by value, so the matrix can't be modified inside the fucntion, only 'outside'. Also, mathcad have the return function as keyword but isn't used.

SudokuRec.zip (24 KiB) downloaded 27 time(s).
SudokuRec.pdf (285 KiB) downloaded 29 time(s).

This other is te recurrent version in SMath: don't works.

SudokuRec.sm (45 KiB) downloaded 32 time(s).

This other is a rewrite of the alyles version.

SudokuBruteForce_lyles.sm (43 KiB) downloaded 47 time(s).

Best regards.
Alvaro.