CODEWITHSUNDEEP
matlabfunctionbinarydecimal
boot-scootin
boot-scootin

Reputation: 12515

Convert decimal to binary in Matlab?

I am converting base-10 numbers to base-2 numbers, and specifying the number of bits I'd like to use to represent these base-10 numbers.

Here's my code for negative numbers:

function output = DTB(decimal,binary)
if decimal < 0
    smallestNum = -(2^(bits-1));

    if decimal < smallestNum
        error('%d cannot be represented in %d bits. Increase the number of bits. ',decimal,bits);
        output = '';
    end

    output = '1';
    bits = bits - 1;

    if smallestNum == decimal
        while bits ~= 0
            output = [output,'0'];
            bits = bits - 1;
        end
    end

    num = smallestNum;
    while num ~= decimal
        num = smallestNum + 2^(bits-1);
        if num > decimal
            output = [output,'0'];
        else
            output = [output,'1'];
            smallestNum = smallestNum + 2^(bits-1);
        end
        bits = bits - 1;
    end

    while bits ~= 0
        output = [output,'0'];
        bits = bits - 1;
    end
end

This works fine. The issue I'm running into (oddly enough, since going from positive decimals to binary should be easier) is with positive integers. It should just be a minor tweak to the negative number algorithm, right? The positive number piece does not work in the case of decimal = 8 and bits = 6, for example (it doesn't work for different powers of 2). What's wrong, here?

Here's the code for positive integers:

if decimal > 0
    largestNum = (2^(bits-1))-1;

    if decimal > largestNum
        error('%d cannot be represented in %d bits. Increase the number of bits. ',decimal,bits);
        output = '';
    end

    % first spot must be zero to show it's a positive number
    output = '0';
    bits = bits - 1;

    largestNum = largestNum + 1;
    num = largestNum;

    while num ~= decimal
        num = largestNum - 2^(bits-1);
        if num > decimal
            output = [output,'0'];
        end
        if num <= decimal
            output = [output,'1'];
            largestNum = largestNum - 2^(bits-1);
        end
        bits = bits - 1;
    end

    while bits ~= 0
        output = [output,'0'];
        bits = bits - 1;
    end

Upvotes: 1

Views: 3873

Answers (2)

DERNI BRAHIM
DERNI BRAHIM

Reputation: 1

you can use this script in matlab:

a=[1 2 3 4;-2 -4 3 4;7 8 9 4];

[c,v]=size(a);

n3=c*v;

word_len=5;%with bits of binary  word

data = reshape(a', n3, 1);

databin= fi(data,1,5);

h=bin(databin)%result

Upvotes: -1

efunkh
efunkh

Reputation: 311

You need to reduce largest num when you put a zero in the output array, because you're essentially starting from a binary array of all ones (ie largestNum). This code worked for me: 

if decimal > 0
largestNum = (2^(bits-1))-1;

if decimal > largestNum
    error('%d cannot be represented in %d bits. Increase the number of bits. ',decimal,bits);
    output = '';
end

% first spot must be zero to show it\'s a positive number
output = '0';
bits = bits - 1;

largestNum = largestNum + 1;
num = largestNum;

while num ~= decimal
    num = largestNum - 2^(bits-1);
    if num > decimal
        output = [output,'0'];
        largestNum = largestNum - 2^(bits-1);
    end
    if num <= decimal
        output = [output,'1'];

    end
    bits = bits - 1;
end

while bits ~= 0
    output = [output,'0'];
    bits = bits - 1;
end
end

I'm not sure what this is for, but I would highly recommend using the built in dec2bin to do this.

Upvotes: 3

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