Hello Monks,

I'm trying to do some matrix handling as fast as possible. Basicly i have a matrix like this 
11	12	13
21	22	23
31	32	33
Now i need to transpose that. Originally i just read the whole matrix into memory as transposed arrays and wrote them out. Now this wont work when transposing to big files. Alternative way was to read one column at a time, but this will take a lot of time (perhaps would be faster to read 10 columns into 10 files, then cat them together).

Alternative way would be to read the whole file and write it out in binary format, allowing fast moving in file ((sys)?seek basicly) to get all numbers in correct order, so i can write the result. But how do i handle this?

I could use open, read, print and seek. Assuming that each column holds a double number (64-bits, right): 
# loop for reading one column
open (BINM,"<:raw");
read (BINM,$number,64);
print OUTM "$number\t";
seek (BINM,64*$columns_number,1);

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Or i could use sysread, syswrite, sysread and sysseek in similar manner as above. However, when i'm reading the original matrix file. 
while (<MATRIX>) {
  chomp;
  my @numbers=split (/\t/,$_);
  # problem
}

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How do i write it out as doubles, into the binary file? Also if following values are also acceptable, how do they complicate things (case of characters could be set, but i'd prefer them to allow any case): 
[+-]?inf
NaN

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In reply to Binary file handling by Hena

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