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ldivide, .\

Left array division

Description

example

x = B.\A divides each element of A by the corresponding element of B. The sizes of A and B must be the same or be compatible.

If the sizes of A and B are compatible, then the two arrays implicitly expand to match each other. For example, if one of A or B is a scalar, then the scalar is combined with each element of the other array. Also, vectors with different orientations (one row vector and one column vector) implicitly expand to form a matrix.

x = ldivide(B,A) is an alternative way to divide A by B, but is rarely used. It enables operator overloading for classes.

Examples

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Create two numeric arrays, A and B, and divide the second array, B, into the first, A.

A = ones(2,3);
B = [1 2 3; 4 5 6];
x = B.\A
x = 2×3

    1.0000    0.5000    0.3333
    0.2500    0.2000    0.1667

Create a scalar, c, and divide it by a numeric array. The result is the same size as the array.

c = 2;
D = [1 2 3; 4 5 6];
x = D.\c
x = 2×3

    2.0000    1.0000    0.6667
    0.5000    0.4000    0.3333

Create a 1-by-2 row vector and 3-by-1 column vector and divide them.

a = 1:2;
b = (1:3)';
b .\ a
ans = 3×2

    1.0000    2.0000
    0.5000    1.0000
    0.3333    0.6667

The result is a 3-by-2 matrix, where each (i,j) element in the matrix is equal to b(i) .\ a(j):

a=[a1a2],b=[b1b2b3],          b.\a=[b1.\a1b1.\a2b2.\a1b2.\a2b3.\a1b3.\a2].

Since R2023a

Create two tables and divide the second table into the first. The row names (if present in both) and variable names must be the same, but do not need to be in the same orders. Rows and variables of the output are in the same orders as the first input.

B = table([1;2],[3;4],VariableNames=["V1","V2"],RowNames=["R1","R2"])
B=2×2 table
          V1    V2
          __    __

    R1    1     3 
    R2    2     4 

A = table([4;2],[3;1],VariableNames=["V2","V1"],RowNames=["R2","R1"])
A=2×2 table
          V2    V1
          __    __

    R2    4     3 
    R1    2     1 

x = B .\ A
x=2×2 table
          V1       V2   
          ___    _______

    R1      1    0.66667
    R2    1.5          1

Input Arguments

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Operands, specified as scalars, vectors, matrices, multidimensional arrays, tables, or timetables. Inputs A and B must either be the same size or have sizes that are compatible (for example, A is an M-by-N matrix and B is a scalar or 1-by-N row vector). For more information, see Compatible Array Sizes for Basic Operations.

  • If A or B is an integer data type, then the other input must be the same integer type or be a scalar double. Operands with an integer data type cannot be complex.

Inputs that are tables or timetables must meet the following conditions: (since R2023a)

  • If an input is a table or timetable, then all its variables must have data types that support the operation.

  • If only one input is a table or timetable, then the other input must be a numeric or logical array.

  • If both inputs are tables or timetables, then:

    • Both inputs must have the same size, or one of them must be a one-row table.

    • Both inputs must have variables with the same names. However, the variables in each input can be in a different order.

    • If both inputs are tables and they both have row names, then their row names must be the same. However, the row names in each input can be in a different order.

    • If both inputs are timetables, then their row times must be the same. However, the row times in each input can be in a different order.

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

Tips

  • The element-wise operators ./ and .\ are related to each other by the equation A./B = B.\A.

  • When dividing integers, use idivide for more rounding options.

  • MATLAB® does not support complex integer division.

Extended Capabilities

GPU Code Generation
Generate CUDA® code for NVIDIA® GPUs using GPU Coder™.

Version History

Introduced before R2006a

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