bsxfun

Apply element-wise operation to two arrays with implicit expansion enabled

Description

example

C = bsxfun(fun,A,B) applies the element-wise binary operation specified by the function handle fun to arrays A and B.

Examples

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Subtract the column mean from the corresponding column elements of a matrix A. Then normalize by the standard deviation.

A = [1 2 10; 3 4 20; 9 6 15];
C = bsxfun(@minus, A, mean(A));
D = bsxfun(@rdivide, C, std(A))
D = 3×3

-0.8006   -1.0000   -1.0000
-0.3203         0    1.0000
1.1209    1.0000         0

In MATLAB® R2016b and later, you can directly use operators instead of bsxfun, since the operators independently support implicit expansion of arrays with compatible sizes.

(A - mean(A))./std(A)
ans = 3×3

-0.8006   -1.0000   -1.0000
-0.3203         0    1.0000
1.1209    1.0000         0

Compare the elements in a column vector and a row vector. The result is a matrix containing the comparison of each combination of elements from the vectors. An equivalent way to execute this operation is with A > B.

A = [8; 17; 20; 24]
A = 4×1

8
17
20
24

B = [0 10 21]
B = 1×3

0    10    21

C = bsxfun(@gt,A,B)
C = 4x3 logical array

1   0   0
1   1   0
1   1   0
1   1   1

Create a function handle that represents the function $f\left(a,b\right)=a-{e}^{b}$.

fun = @(a,b) a - exp(b);

Use bsxfun to apply the function to vectors a and b. The bsxfun function expands the vectors into matrices of the same size, which is an efficient way to evaluate fun for many combinations of the inputs.

a = 1:7;
b = pi*[0 1/4 1/3 1/2 2/3 3/4 1].';
C = bsxfun(fun,a,b)
C = 7×7

0    1.0000    2.0000    3.0000    4.0000    5.0000    6.0000
-1.1933   -0.1933    0.8067    1.8067    2.8067    3.8067    4.8067
-1.8497   -0.8497    0.1503    1.1503    2.1503    3.1503    4.1503
-3.8105   -2.8105   -1.8105   -0.8105    0.1895    1.1895    2.1895
-7.1205   -6.1205   -5.1205   -4.1205   -3.1205   -2.1205   -1.1205
-9.5507   -8.5507   -7.5507   -6.5507   -5.5507   -4.5507   -3.5507
-22.1407  -21.1407  -20.1407  -19.1407  -18.1407  -17.1407  -16.1407

Input Arguments

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Binary function to apply, specified as a function handle. fun must be a binary (two-input) element-wise function of the form C = fun(A,B) that accepts arrays A and B with compatible sizes. For more information, see Compatible Array Sizes for Basic Operations. fun must support scalar expansion, such that if A or B is a scalar, then C is the result of applying the scalar to every element in the other input array.

In MATLAB® R2016b and later, the built-in binary functions listed in this table independently support implicit expansion. With these functions, you can call the function or operator directly instead of using bsxfun. For example, you can replace C = bsxfun(@plus,A,B) with A+B.

FunctionSymbolDescription
plus

+

Plus

minus

-

Minus

times

.*

Array multiply

rdivide

./

Right array divide

ldivide

.\

Left array divide

power

.^

Array power

eq

==

Equal

ne

~=

Not equal

gt

>

Greater than

ge

>=

Greater than or equal to

lt

<

Less than

le

<=

Less than or equal to

and

&

Element-wise logical AND

or

|

Element-wise logical OR

xor

N/A

Logical exclusive OR

bitand

N/A

Bit-wise AND

bitor

N/A

Bit-wise OR

bitxor

N/A

Bit-wise XOR

max

N/A

Binary maximum

min

N/A

Binary minimum

mod

N/A

Modulus after division

rem

N/A

Remainder after division

atan2

N/A

atan2d

N/A

Four-quadrant inverse tangent; result in degrees

hypot

N/A

Square root of sum of squares

Example: C = bsxfun(@plus,[1 2],[2; 3])

Data Types: function_handle

Input arrays, specified as scalars, vectors, matrices, or multidimensional arrays. Inputs A and B must have compatible sizes. For more information, see Compatible Array Sizes for Basic Operations. Whenever a dimension of A or B is singleton (equal to one), bsxfun virtually replicates the array along that dimension to match the other array. In the case where a dimension of A or B is singleton, and the corresponding dimension in the other array is zero, bsxfun virtually diminishes the singleton dimension to zero.

Data Types: single | double | uint8 | uint16 | uint32 | uint64 | int8 | int16 | int32 | int64 | char | logical
Complex Number Support: Yes

Tips

• It is recommended that you replace most uses of bsxfun with direct calls to the functions and operators that support implicit expansion. Compared to using bsxfun, implicit expansion offers faster speed of execution, better memory usage, and improved readability of code. For more information, see Compatible Array Sizes for Basic Operations.