MATLAB: Getting very weird number from hex2dec()

doublehex2dec

Hello,

I am attempting to convert large matrices of doubles to hex. I have an S matrix [2048 x 984] full of zeros

If I do this

>> dec2hex(s1a(1,3))
ans =
0

which is what should happen. However If I do this…..

HexS1a = ones(2048,984);
for aa = 1:984
    for bb = 1:2048
    HexS1a(bb,aa) = HexS1a(bb,aa)*dec2hex(s1a(bb,aa));
    end
end

I get a matrix of "48"'s not zeros. The type is double. Can anyone explain this? It's driving me nuts!

Best Answer

dec2hex(sla(1,3)) is not producing a digit zero: it is producing the string '0' . The numeric code for the character '0' happens to be 48. char(48) = '0'

ones(2048,984) is a double precision datatype. When you store a character to a double precision data type, the character gets converted to its numeric code.

If you are planning to multiply hex digits then you will need something more sophisticated that the "*" operator.

Related Solutions

MATLAB: How to split binary and convert to decimal

aaa = ['0000001101001011';'0000011010001010';'0000100100111100'];
bbb=[aaa(:,1:8); aaa(:,9:16)];
bbb=reshape(bin2dec(bbb),3,[]);

MATLAB: Hex-to-Binary conversion always outputting 48 or 49

"_my BinaryMat consists of 48s and 49s instead of 1s and 0s."_

I didn't try to read the code but somewhere you've converted the char return to its internal representation. '48' is the decimal value of the character '0'

>> double('0')
ans =
    48
>> char([48;49])
ans =
  2×1 char array
    '0'
    '1'
>> 
>> dec2bin(hex2dec('F'))
ans =
  '1111'
>> double(ans)
ans =
  49    49    49    49
>>

ADDENDUM

I think you can get to useful result quite a lot more simply...see if the following won't serve for your purposes:

function bin=hexmat2bin(HexMat)
  % returns cell array of binary bits in input hex array of characters
  % output cell array is same shape as input char() array
  %

  % hexarray=['1','2','0';'A','C','8';'9','6','F'];
  % bincell=hexmat2bin(hexarray)
  %  bincell =
  %
  %  {'0001'}    {'0010'}    {'0000'}
  %  {'1010'}    {'1100'}    {'1000'}
  %  {'1001'}    {'0110'}    {'1111'}
    [m,n]=size(HexMat);
    HexC=mat2cell(HexMat,ones(1,m),ones(1,n));
    bin=reshape(cellstr(dec2bin(hex2dec(HexC),4)),m,[]);
  end

For your sample input (which I used as the help file example as well) one gets

>> BinaryMat=hexmat2bin(HexMat)
BinaryMat =
  3×3 cell array
    {'0001'}    {'0010'}    {'0000'}
    {'1010'}    {'1100'}    {'1000'}
    {'1001'}    {'0110'}    {'1111'}
>>

All you need to do is to dereference the cell array to retrieve any given character string desired--remember that's using the "curlies" instead of ordinary parentheses:

>> BinaryMat{1,2}
ans =
  '0010'
>>

Best Answer

Related Solutions

MATLAB: How to split binary and convert to decimal

MATLAB: Hex-to-Binary conversion always outputting 48 or 49

Related Question