isreal
Determine whether array uses complex storage
Syntax
Description
Examples
Determine Whether Matrix Contains All Real Values
Define a 3-by-4 matrix, A
.
A = [7 3+4i 2 5i;... 2i 1+3i 12 345;... 52 108 78 3];
Determine whether the array is real.
tf = isreal(A)
tf = logical
0
Since A
contains complex elements, isreal
returns false.
Define Complex Number with Zero-Valued Imaginary Part
Use the complex
function to create a scalar, A
, with zero-valued imaginary part.
A = complex(12)
A = 12.0000 + 0.0000i
Determine whether A
is real.
tf = isreal(A)
tf = logical
0
A
is not real because it has an imaginary part, even though the value of the imaginary part is 0
.
Determine whether A
contains any elements with zero-valued imaginary part.
~any(imag(A))
ans = logical
1
A
contains elements with zero-valued imaginary part.
Computation Resulting in Zero-Valued Imaginary Part
Define two complex scalars, x
and y
.
x=3+4i; y=5-4i;
Determine whether the addition of two complex scalars, x
and y
, is real.
A = x+y
A = 8
MATLAB® drops the zero imaginary part.
isreal(A)
ans = logical
1
A
is real since it does not have an imaginary part.
Find Real Elements in Cell Array
Create a cell array.
C{1,1} = pi; % double C{2,1} = 'John Doe'; % char array C{3,1} = 2 + 4i; % complex double C{4,1} = ispc; % logical C{5,1} = magic(3); % double array C{6,1} = complex(5,0) % complex double
C=6×1 cell array
{[ 3.1416]}
{'John Doe' }
{[2.0000 + 4.0000i]}
{[ 0]}
{3x3 double }
{[5.0000 + 0.0000i]}
C
is a 1-by-6 cell array.
Loop over the elements of a cell array to distinguish between real and complex elements.
for k = 1:6 x(k,1) = isreal(C{k,1}); end x
x = 6x1 logical array
1
1
0
1
1
0
All but C{3,1}
and C{6,1}
are real arrays.
Input Arguments
A
— Input array
scalar | vector | matrix | multidimensional array
Input array, specified as a scalar, vector, matrix, or multidimensional array.
For numeric data types, if
A
does not have an imaginary part,isreal
returnstrue
; ifA
does have an imaginary partisreal
returnsfalse
.For
duration
,calendarDuration
,logical
, andchar
data types,isreal
always returnstrue
.For
string
,table
,cell
,struct
,datetime
,function_handle
, andobject
data types,isreal
always returnsfalse
.
Data Types: single
| double
| int8
| int16
| int32
| int64
| uint8
| uint16
| uint32
| uint64
| logical
| char
| string
| struct
| table
| cell
| datetime
| duration
| calendarDuration
| function_handle
Complex Number Support: Yes
Tips
To check whether each element of an array
A
is real, useA == real(A)
.isreal(complex(A))
always returnsfalse
, even when the imaginary part is all zeros.~isreal(x)
detects arrays that have an imaginary part, even if it is all zeros.
Extended Capabilities
C/C++ Code Generation
Generate C and C++ code using MATLAB® Coder™.
GPU Code Generation
Generate CUDA® code for NVIDIA® GPUs using GPU Coder™.
HDL Code Generation
Generate VHDL, Verilog and SystemVerilog code for FPGA and ASIC designs using HDL Coder™.
Thread-Based Environment
Run code in the background using MATLAB® backgroundPool
or accelerate code with Parallel Computing Toolbox™ ThreadPool
.
This function fully supports thread-based environments. For more information, see Run MATLAB Functions in Thread-Based Environment.
GPU Arrays
Accelerate code by running on a graphics processing unit (GPU) using Parallel Computing Toolbox™.
The isreal
function
fully supports GPU arrays. To run the function on a GPU, specify the input data as a gpuArray
(Parallel Computing Toolbox). For more information, see Run MATLAB Functions on a GPU (Parallel Computing Toolbox).
Distributed Arrays
Partition large arrays across the combined memory of your cluster using Parallel Computing Toolbox™.
This function fully supports distributed arrays. For more information, see Run MATLAB Functions with Distributed Arrays (Parallel Computing Toolbox).
Version History
Introduced before R2006a
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