sign
Sign function (signum function)
Syntax
Description
Examples
Find Sign Function
Find the sign function of a number.
sign(2)
ans = 1
Find the sign function of the values of a vector.
V = [-11 0 1.5 Inf NaN]; sign(V)
ans = 1×5
-1 0 1 1 NaN
Find the sign function of the values of a matrix.
M = magic(3) - 5; sign(M)
ans = 3×3
1 -1 1
-1 0 1
-1 1 -1
Find the sign function of a complex number.
z = 4 - 3*i; sign(z)
ans = 0.8000 - 0.6000i
Plot Sign Function
Plot the sign function and show its behavior at the zero-crossing. Use eps
to represent values just above and below 0
.
x = [-5 -eps(1) 0 eps(1) 5];
y = sign(x);
plot(x,y)
ylim([-2 2])
grid on
Plot Real and Imaginary Parts of Sign Function
Plot real and imaginary parts of the sign function over and .
First, create a mesh of values over -3 < x < 3
and -3 < y < 3
using meshgrid
. Then create complex numbers from these values using z = x + 1i*y
.
v = -3:0.1:3; [x, y] = meshgrid(v); z = x + 1i*y;
Find the real and imaginary parts of the sign function of z
.
s = sign(z); re = real(s); im = imag(s);
Plot the real and imaginary parts.
surf(x,y,re) title('Real part of sign function') xlabel('x') ylabel('y')
figure(2) surf(x,y,im) title('Imaginary part of sign function') xlabel('x') ylabel('y')
Input Arguments
x
— Input
scalar | vector | matrix | multidimensional array
Input, specified as a scalar, vector, matrix, or multidimensional array.
If an element of x
is NaN
, then
sign
returns NaN
in the
corresponding element of the output.
Data Types: single
| double
| int8
| int16
| int32
| int64
| uint8
| uint16
| uint32
| uint64
| logical
| duration
Complex Number Support: Yes
Extended Capabilities
Tall Arrays
Calculate with arrays that have more rows than fit in memory.
The
sign
function fully supports tall arrays. For more information,
see Tall Arrays.
C/C++ Code Generation
Generate C and C++ code using MATLAB® 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 sign
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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