Element-wise interval conformity check

3 views (last 30 days)
Hello I have a Matrix
A=[1.0,2.0,0.7;1.2,3.0,1.0;0.8,1.1,0];
and an Interval
lower = 0.75;
upper = 1.25;
Matrix R should give me either 1 if the corresponding element of A is within the interval, or else 0:
R=[1,0,0;1,0,1;1,1,0];
Is there any way to do this without a loop?

Accepted Answer

Stephen23
Stephen23 on 4 May 2015
Edited: Stephen23 on 4 May 2015
Do not use lower and upper as variable names, as these are both names of inbuilt functions.
MATLAB lets you perform basic operations like this on the entire array (which is called code vectorization), so this comparison can be done directly using the relational operators, without any loops:
>> A = [1.0,2.0,0.7;1.2,3.0,1.0;0.8,1.1,0];
>> lwr = 0.75;
>> upr = 1.25;
>> R = lwr<=A & A<=upr
R =
1 0 0
1 0 1
1 1 0
This is covered in the introduction tutorials to MATLAB:

More Answers (1)

Purushottama Rao
Purushottama Rao on 4 May 2015
Without looping, this can be done by accessing each element of a matrix and processing with an if condition. That makes lot of hand written code compared to looping.
  1 Comment
Stephen23
Stephen23 on 4 May 2015
Edited: Stephen23 on 4 May 2015
This is misleading and very poor advice that shows a basic misunderstanding of how to use MATLAB. Simply reading the documentation for the relational operators makes it clear that they operate on whole arrays at once, for example le states " A <= B returns a logical array with elements set to logical 1 (true) where A is less than or equal to B..." note the word array in that sentence. The examples in the documentation also illustrate this:
A = [1 12 18 7 9 11 2 15];
A <= 12
ans =
1 1 0 1 1 1 1 0
This means that no if statements or "lot of hand written code compared to looping" is required. Please learn about code vectorization.

Sign in to comment.

Categories

Find more on Entering Commands in Help Center and File Exchange

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!