CODEWITHSUNDEEP
matlabmatlab-deployment
user3644850
user3644850

Reputation: 3

Extracting digits after decimal MATLAB

I am representing a chaotic number with 15 digits after decimal i.e format long in matlab and i want to extract 3 numbers each containing 5 digits from the chaotic number. i.e if chaotic no. is 0.d1d2...d15 then i want (d1..d5),(d6..d10) & (d11..d15). it is always rounding off.I have written the following code.

num=x(n);
a1=floor(num*10^5);
disp('a1');
disp(a1);
a2=floor(num*10^10-a1*10^5);
disp(a2);
num=floor(num*10^15);
a3=mod(num,100000);
disp('a3');
disp(a3);

and the output is

0.320446597556797

a1
   32044
a2
   65975

a3
   56796

its showing a3 as 56796 but i want 56797.

please help!!!

Upvotes: 0

Views: 1026

Answers (3)

Luis Mendo
Luis Mendo

Reputation: 112689

The problem is, very likely, that each operation you do to extract a group of digits introduces a small error, which is reflected in the last digit.

An alternative approach that avoids this:

num = pi; %// for example
str = num2str(num,'%0.15f'); %// string representation with 15 decimal digits
str = str(find(str=='.')+1:end); %// keep only digits after decimal point
a = base2dec(reshape(str,5,[]).',10); %'// convert string parts into numbers

Upvotes: 2

Divakar
Divakar

Reputation: 221574

Try this approach using strings -

n = 0.320446597556797 %// Input decimal number

t1 = num2str(n,'%1.15f')
t2 = strfind(t1,'.')
a = str2num(reshape(t1(t2+1:end),5,[])') %// output as a single matrix

Thanks to @Luis for the reshape idea! Hope you won't mind Luis!

Upvotes: 2

MZimmerman6
MZimmerman6

Reputation: 8603

It is probably a rounding error but if you really want those specific values, simply cast to a string and then rip the string apart. Something simple like below

a = 0.320446597556797;
format longg
aStr = num2str(a,'%1.15f');
decimals = regexp(aStr,'\.','Split');
decimals = decimals{2};

a1 = str2double(decimals(1:5));
a2 = str2double(decimals(6:10));
a3 = str2double(decimals(11:15));

Upvotes: 0

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