Finding location of specific element from a MATRIX returns '0×1 empty double column vector'

Hi everyone,

I have a matrix and I'm trying to find location of some specific elements but it gives me no answer. My code:

[i,j] = find(a==23.5975) % it can be clearly seen in the figure that this value is present in the 
% 1st row and 3rd column. but it gives the following result. 
i =
  0×1 empty double column vector

j =
  0×1 empty double column vector
  

I'll be gratefu for any help, thank you.

Answer 1

[Chunru]

[i,j] = find(abs(a-23.5975)<1e-20)

[Zhou Ci]

It still returns the same answer

i =
  0×1 empty double column vector
j =
  0×1 empty double column vector

[Chunru]

Then change 1e-20 to a slightly larger number, say 1e-6

[Zhou Ci]

Unfortunately, it also didn't work.

[Chunru]

What tolerance have you tried? Make it bigger: 1e-4

[Chunru]

rng(1);
a = rand(4)

a = 4×4

0.4170 0.1468 0.3968 0.2045 0.7203 0.0923 0.5388 0.8781 0.0001 0.1863 0.4192 0.0274 0.3023 0.3456 0.6852 0.6705

[i,j] = find(abs(a-0.1863)<1e-3)

i = 3

j = 2

[i,j] = find( a== 0.1863)

i =

  0×1 empty double column vector


j =

  0×1 empty double column vector

[Walter Roberson]

target = 0.1863

target = 0.1863

rng(1);
a = rand(4)

a = 4×4

0.4170 0.1468 0.3968 0.2045 0.7203 0.0923 0.5388 0.8781 0.0001 0.1863 0.4192 0.0274 0.3023 0.3456 0.6852 0.6705

[found, idx] = ismembertol(target, a)

found = logical
   0

idx = 0

[~, minidx] = min(abs(target - a(:)));
a(minidx)

ans = 0.1863

a(minidx) - target

ans = -3.9789e-05

[found, idx] = ismembertol(target, a, 1e-4)

found = logical
   1

idx = 7

[Zhou Ci]

Working now, Thanks alot!