Base conversion of very large integers

Base conversion of very large integers

Description

This set of functions perform base conversion of very large integers, well beyond the standard Matlab functions that are limited to 52bits. The input and output numbers are represented by strings (and not numbers) to avoid the Matlab limitations.
The main functions are: dec2hex_long, dec2oct_long, dec2bin_long, hex2dec_long, oct2dec_long and bin2dec_long

• MATLAB release: MATLAB 7.1.0 (R14SP3)

[Kok-Wah Lee]

Help to fulfill many demands.

[Christopher Hazel]

 

[Christopher Hazel]

The bin2dec_long file did not account for the case where the string input contained all zeroes, so I added the following code just before the "conversion setup" lines:

if str2num(str_in)==0;
    str_out=0;
else
%conversion setup
...(file code)
end

[Michael]

This seems really useful but the answers are the same as de2bi for powers of two larger than 53. Please notice below:

>> uint64(2^60-1)

ans =

  1152921504606846976

>> dec2bin_long('1152921504606846976',60)

ans =

1000000000000000000000000000000000000000000000000000000000000

>> dec2bin_long('1152921504606846976')

ans =

1000000000000000000000000000000000000000000000000000000000000

>> uint64(2^53-1)

ans =

     9007199254740991

>> dec2bin_long('9007199254740991')

ans =

11111111111111111111111111111111111111111111111111111

>> uint64(2^55-1)

ans =

    36028797018963968

>> dec2bin_long('36028797018963968')

ans =

10000000000000000000000000000000000000000000000000000000

[John D'Errico]

Of course there is no need to be limited by this code, when vpi exists on the file exchange. For example, here is the result of applying it to a 60 decimal digit number, something that is rather difficult to do with other codes.

vpi2bin(vpi('123456789012345678901234567890123456789012345678901234567890'))

ans =
10011101010101111010100000100111001001011110000011110011000100001011100111111100001111010010000110111100011000011011110110100100111001000110011001111111100011001011011001110001111110000101011010010

And if you want to convert to any other base, vpi2base works nicely there too.

vpi2base(vpi('123456789012345678901234567890123456789012345678901234567890'),256)
ans =
  19 170 245 4 228 188 30 98 23 63 135 164 55 140 55 180 156 140 207 241 150 206 63 10 210

A good point is, for a tool that does as little as this does, it is rather complicated, requiring over 20 m-files to accomplish that task.

[Michael]

OK just saw VPI - never heard of that before... thank you