find the nearest value

Hi!

Can someone help with this problem please.....

if for example, q = [1 3 6 8 10 15]

find(q==8) returns ans = 4

find(q==9) returns Empty matrix: 1-by-0 because there is no value 9

...how do I query, find the value in q that is nearest to 9??

Answer 1

[Iain]

 q = [1 3 6 8 10 15];
 v = 9;
 [~,ans] = (min(abs(q - v)))

[crispin Donnelly]

nice! thanks

Answer 2

[mohamed azuan wahari]

find nearest value on matrix

Can someone help with this problem please.....

for example

a= 1250

matrix_b=[98 125 945 1005;
          105 204 1105 1249;
          200 250 1299 1450;
          300 450 1350 1850]

want to find nearest equal or greater than a=1250

and the answer should be 1299

[Walter Roberson]

   v = sort(matrix_b(:));
   vidx = floor(interp1(v, 1:length(v), a, 'linear', 'extrap'));
   if vidx ~= 0
      result = b(vidx);
   end

Or

   v = sort(matrix_b(:));
   vidx = find(v >= a, 1, 'first');
   if ~isempty(vidx)
     result = v(vidx);
   end

or

   v = sort(matrix_b(:));
   [~, vidx] = histc(a, v);
   if vidx ~= 0
     result = v(vidx);
   end

The middle of these is probably the easiest to think about, but it cannot be generalized to a list of a values like the other ones can (aside from the testing to be sure that a result was found.)

[Walter Roberson]

If you have R2016a or later, then

v = sort(matrix_b(:));
result = interp1(v, v, a, 'previous');