@Preben Alsholm You are right, the sequence B is not used in the procedure inv_sierp, but it is given in the paper's code. The same for the x[i].

@Preben Alsholm thanks for your interest and help.

Please, find attached a file with some modifications of the "sierp" procedure. I am almost sure that the code given in the above paper is not fine at all. Now, the procedure "sierp" plot something "similar" to the figure of the paper (I am not sure that this procedures works fine now). Also, i have added the "inv_sierp", which  does not work.

I reiterate my gratitude for your help.

Sierp_v1.mw

@Preben Alsholm Thanks for you commet. I know that somethig is (obviously) wrong, but I don't know if the cause is my code or the algorithm given in the paper,

Thanks.

@Axel Vogt  Many thnaks for your interest and help. I have the Brent's book which I think you metioned.

@Carl Love First, many thnaks for your suggestion, I have the book R. Brent, Algorithms for minimization without derivatives, Prentince Hall Inc. 1973

However, I don't undestand at all such code. In this URL https://people.math.sc.edu/Burkardt/f_src/brent/brent.f90 is teh code in fortra99, which seems to can be easily adapted to maple (almost a coy/paste, i think).

@C_R  many thanks for your useful help. With slight modifications, the code seems to work ok.

brent.mw

I reiterate my gratitude for your help.

@acer thanks!

@vv Thanks!! Nice, really nice code!

@mmcdara  Thanks for your code!

Hi!!

It seems that I have solved the problem: In the file IFF_v2.mw, I have changed  global NunFun:=n-1 by global NunFun:=n  in the procedure "CreateDataSet".

@acer many thanks! Now it works.

Great @Rouben Rostamian  !!! It seems that your code works fine..Thanks!! 

@vv thanks.

As you say, "t it is easy to implement a Lebesgue filling curve in any dimension (just a few lines in Maple". In fact, you are a post with this issue:

https://www.mapleprimes.com/questions/220980-Convert-Peano-Curve-Into-A-Function

@vv thanks for your reply. Your code is for Maple 2020, right? In the paper linked in my post, the code (in C) is for the n-dimensional Hilbert curve, and for its  "pseudo-inverse"

@Carl Love The version is  Maple 17.00