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Embiggen

version 1.0.0.0 (2.65 KB) by Patrick Mineault
Add (or multiply, divide, etc) a matrix A to a vector b with the simple syntax A + Embiggen(b)

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Updated 13 May 2010

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Embiggen is a class that makes Matrix-vector operations easier by virtually matching the size of a vector b to the size of amatrix A. This allows for such code as:

C = A + Embiggen(b)

Here A is a matrix (for example of size 100x50)
b is a vector (for example of size 100x1)

And the equation is understood as (in index notation)
C_ij = A_ij + b_j

Which is more readable than the alternatives:

C = A + b*ones(1,size(A,2));
C = A + repmat(b,1,size(A,2));
C = bsxfun(@plus,A,b);

Under the hood the "big matrix B" is never actually created, as bsxfun is used; however Embiggen avoids the ackward reverse polish notation style of bsxfun .

A neat example:

%Center and scale columns of a matrix
A = randn(50,60);
A = A - Embiggen(mean(A));
A = A ./ Embiggen(std(A));

mean(A) %vector of zeros
std(A) %vector of ones

The following operators are implemented:

A + Embiggen(b)
A - Embiggen(b)
A .* Embiggen(b)
A ./ Embiggen(b)
A .\ Embiggen(b)

And the logical operations:

A == Embiggen(b)
A ~= Embiggen(b)
A < Embiggen(b)
A > Embiggen(b)
A <= Embiggen(b)
A >= Embiggen(b)
A & Embiggen(b)
A | Embiggen(b)
xor(A, Embiggen(b))

As well as the functions:
max(A,Embiggen(b))
min(A,Embiggen(b))
rem(A,Embiggen(b))
mod(A,Embiggen(b))
atan2(A,Embiggen(b))
hypot(A,Embiggen(b))

Embiggen also works between any two multidimensional arrays A and B as long as each dimension of A and B is equal to each other, or equal to one.

Embiggen does not redefine any core Matlab classes, unlike other solutions (for example bsxops).

Comments and Ratings (2)

Ian

David Young

MATLAB Release Compatibility
Created with R2008a
Compatible with any release
Platform Compatibility
Windows macOS Linux
Acknowledgements

Inspired by: bsxops