Question Fortran like 2D array

Hi all,
I try to write code that stores 2D array in a row, but I want to access to it by [][] operator. The code is

Code:

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double** arr;
int x=19,y=17;

arr=(double**)malloc((x+1)*sizeof(double*))+1;
arr[-1]=(double*)calloc(y*x,sizeof(double));
for(int i=0;i!=x;i++)
  arr[i]=&arr[-1][i*y];

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May be there is an mistake causing errors in my numerical computation. Valgrind says there are no errors. Pleas hlep.
P.S.: I hope you can understand my english

Use Boost.Multi_Array. It does the memory management and index computation for you, and you can choose whether you want row-major (Fortran) or column-major (C) format.

http://www.boost.org/libs/multi_array/doc/index.html

I used Boost, but it was too slow

Quote:

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I used Boost, but it was too slow

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Boost is used in many high performance applications and games. It is not slow.

On a proper inlining compiler, MultiArray should have just about zero overhead over a manual implementation of index computation - perhaps even be faster. It should definitely be faster than your nested allocation.

I was surpriced too. I used Boost.MultiArray library only and the performance was poor (may be because of bad ussage). Using standard C++ array shows better performance. Finally, fortran arrays are faster (as I heard), so I want to write function that stores a matrix in a vector.

Quote:

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Originally Posted by TauWich

Finally, fortran arrays are faster (as I heard)

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Technically impossible. Raw arrays are as fast as the hardware allows.

Ok, i shall read more about MultiArray library to know where the error was. Many thanks for replys