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version (6.54 KB) by James Tursa
bsxfun is a functional substitute for MATLAB intrinsic of the same name


Updated 11 Feb 2008

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A poor-man's replacement for bsxfun for those users with earlier versions of MATLAB that do not have this intrinsic function available to them. Uses the mex routine bsxarg to physically generate the singleton expanded arrays, and then calls the function. This bsxfun m-file function is not as fast as the MATLAB intrinsic bsxfun (in some cases several times slower), but at least it gives you the same functionality.

bsxfun will apply an element-by-element binary operation to two arrays with singleton expansion enabled.

bsxfun is an m-file function that mimics the MATLAB intrinsic bsxfun. The m-file bsxfun differs from the MATLAB intrinsic bsxfun in the following ways:
- Limited to 12 dimensions
- Allows the 1st input to be a char string as well as a function handle
- Physically does the singleton expansion of each input array
- Requires the use of the bsxarg c-mex routine (included with this post for convenience)

This bsxfun m-file is mainly intended for users with older versions of MATLAB that do not have the MATLAB intrinsic bsxfun available.

REQUIREMENT: You must build bsxarg first (see bsxarg.c file)

The following are the relavent excerpts from the MATLAB doc:


C = bsxfun(fun,A,B)


C = bsxfun(fun,A,B) applies an element-by-element binary operation to arrays A and B, with singleton expansion enabled. fun is a function handle or a character string specifying the name of a binary function, and can either be an M-file function or one of the following built-in functions:

@plus Plus
@minus Minus
@times Array multiply
@rdivide Right array divide
@ldivide Left array divide
@power Array power
@max Binary maximum
@min Binary minimum
@rem Remainder after division
@mod Modulus after division
@atan2 Four quadrant inverse tangent
@hypot Square root of sum of squares
@eq Equal
@ne Not equal
@lt Less than
@le Less than or equal to
@gt Greater than
@ge Greater than or equal to
@and Element-wise logical AND
@or Element-wise logical OR
@xor Logical exclusive OR

If an M-file function is specified, it must be able to accept two input arrays of the same size as the result C.

Each dimension of A and B must either be equal to each other, or equal to 1. Whenever a dimension of A or B is singleton (equal to 1), the array is replicated along the dimension to match the other array. The array may be diminished if the corresponding dimension of the other array is 0.

The size of the output array C is equal to:

max(size(A),size(B)).*(size(A)>0 & size(B)>0).

The bsxfun m-file will, of course, clash with the actual MATLAB intrinsic of the same name, but this is intentional and by design.

Cite As

James Tursa (2021). bsxfun (, MATLAB Central File Exchange. Retrieved .

MATLAB Release Compatibility
Created with R2006a
Compatible with any release
Platform Compatibility
Windows macOS Linux

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