The way I solved this was to declare an empty array:

Array<double> A;

and then grow it as required as the data is read, using resizeAndPreserve. If you read from a file it is better to grow it in chunks, and at the end shrink to size, rather than growing element by element:

A.resize(500); // make room for 500 elements
i=0;
while(!file.eof()) // read to the end of the file
        {
                file >> A(i);
                i++;
                if(i>=A.size()) // make room for more elements if needed
                        A.resizeAndPreserve(i+500);
        }
A.resizeAndPreserve(i); //shrink to the correct size when finished

I am typing by memory, so there are probably some mistakes, but you get the idea. You will have to play with the size of the chunks to get the optimal value for the application you have in hand.

Hope this helps.


Carlos A. Rega, PhD
Development Scientist
Malvern Instruments Ltd
Grovewood Rd, Malvern
WR14 1XZ

Tel: +44 (0)1684 581 304
Fax: +44 (0)1684 892 789

e-mail: carlos.rega@malvern.co.uk


Shmuel Brody <sbrody@cs.huji.ac.il>
Sent by: blitz-support-bounces@oonumerics.org

16/07/2004 10:08
Please respond to Support list for Blitz++

       
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        cc:        
        Subject:        [Blitz-support] arrays with dimension only known at runtime.



Is there any way to declare Arrays/TinyVectors when the number of
dimensions in only known at runtime? for instance, read from a file or
user input?


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