Problem using the FIND function to identify the position of a negative decimal number.

Hello.

I need to find the position of a negative decimal number in a vector. The code I've used is as follows:

a = -2:0.05:0;
num = -0.95;
position = find(a==-0.95);

The problem is with some numbers like the one set in num. Although the number exists within the a vector, the result I get is:

1-0 empty double row vector

What could be the problem? and how can I fix it?. Thanks.

Best regards

Answer 1

[Matt J]

The numbers you are comparing differ by small floating point errors,

>> a(22)-(-0.95)

ans =

  -1.1102e-16

Use ismembertol, instead.

  >> [~,position]=ismembertol(num,a)

position =

    22

[Matt J]

Or,

>> position=find(abs(num-a)<=1e-6)

position =

    22

[Stanislao Pinzón]

Thanks.

Answer 2

[Image Analyst]

See the FAQ Why_is_0.3_-_0.2_-_0.1_.28or_similar.29_not_equal_to_zero?