MATLAB: Do I get a warning about ‘Integer Operands Are Required for Colon Operator When Used as Index’

MATLAB

Why do I get the following error message:

 Warning: Integer operands are required for colon operator when used as index.

Best Answer

Explanation:

You have used a noninteger value as one of the parameters (starting value, increment, or stopping value) for the colon (:) operator when using it to create a vector of indices to reference into a function.

Common causes:

You performed computations to obtain the starting or stopping values for the indexing but the result of those computations was not exactly an integer.

Solution:

Modify the index computations using the FIX, FLOOR, CEIL, or ROUND functions to ensure that the indices are integers. You can test if a variable contains an integer by comparing the variable to the output of the ROUND function operating on that variable when MATLAB is in debug mode on the line containing the variable.

http://www.mathworks.com/help/techdoc/ref/fix.html

http://www.mathworks.com/help/techdoc/ref/floor.html

http://www.mathworks.com/help/techdoc/ref/ceil.html

http://www.mathworks.com/help/techdoc/ref/round.html

Example demonstrating this error:

IntegerOperandsRequired.m

Related Solutions

MATLAB: “Warning: Integer operands are required for colon operator when used as index” in fft

N1 is odd, so N1/2 is a fraction. Add 1 to that and it is still a fraction. You are then trying to index from 1 to that fraction. That will give you a warning.

You need to either prevent N1 from being odd, or else you need to use floor() or fix() or round() on the N1/2 so that it is no longer a fraction

MATLAB: Matlab integer format for answer

Try a function, like int32(), fix(), ceil(), floor(), uint8(), int32(round()), etc.

a = (2+24)/(4*3) % Floating point.
aInteger = int32(a)
whos aInteger; % int32
aInteger = round(a)
whos aInteger; % Double


aInteger = floor(a)
whos aInteger; % Double
aInteger = ceil(a)
whos aInteger; % Double
aInteger = fix(a)
whos aInteger; % double
aInteger = uint16(a)
whos aInteger; % uint16

Note that with round(), ceil(), floor(), and fix() you will end up with a double but with no fractional part. If you want an actual integer, you have to cast to an integer data type with int32(), int16(), etc.

Best Answer

Related Solutions

MATLAB: “Warning: Integer operands are required for colon operator when used as index” in fft

MATLAB: Matlab integer format for answer

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