How to retrieve first 4 digits after decimal point?

Question

Abdul Gaffar 2019-12-4

评论： Star Strider 2019-12-4

I have to retrieve first 4 digits after decimal point in HH band of the following code:

img = imread('cameraman.tif');

a = img(1:8,1:8);

[LL,LH,HL,HH] = dwt2(a,'db4');

Moreover, how can I fetch more than 4 digits (after decimal) in the same HH band ?

Answer 1

Star Strider 2019-12-4

One approach:

x = pi
AfterDecimal = rem(x,1)
FirstFour = fix(AfterDecimal*1E+4)*1E-4

producing:

x =
   3.141592653589793
AfterDecimal =
   0.141592653589793
FirstFour =
   0.141500000000000

Abdul Gaffar 2019-12-4

Thanks, and how to retrieve last 4 digits?

Star Strider 2019-12-4

The easiest way to do that is to convert it to a character array and index the last four digits, then convert it back to a numerical variable:

xstr = num2str(AfterDecimal,15);
LastFour = str2double(xstr(end-3:end))

producing:

LastFour =
   9793

Experiment to get different results.