eye

Identity matrix

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Syntax

E = eye(sz,arraytype)
E = eye(sz,datatype,arraytype)

E = eye(sz,'like',P)
E = eye(sz,datatype,'like',P)

C = eye(sz,codist)
C = eye(sz,datatype,codist)
C = eye(sz,___,codist,'noCommunication')
C = eye(sz,___,codist,'like',P)

Description

E = eye(sz,arraytype) creates an arraytype identity matrix with underlying class of double, with ones on the main diagonal and zeros elsewhere.

E = eye(sz,datatype,arraytype) creates an arraytype identity matrix with underlying class of datatype, with ones on the main diagonal and zeros elsewhere.

The size and type of array are specified by the argument options according to the following table.

ArgumentValuesDescriptions
sznSpecifies array size as an n-by-n matrix.
m,nSpecifies array size as an m-by-n matrix.
[m n]
arraytype'distributed'Specifies distributed array.
'codistributed'Specifies codistributed array, using the default distribution scheme.
'gpuArray'Specifies gpuArray.
datatype'double' (default), 'single', 'int8', 'uint8', 'int16', 'uint16', 'int32', 'uint32', 'int64', or 'uint64'Specifies underlying class of the array, i.e., the data type of its elements.

E = eye(sz,'like',P) creates an identity matrix of the same type and underlying class (data type) as array P.

E = eye(sz,datatype,'like',P) creates an identity matrix of the specified underlying class (datatype), and the same type as array P.

C = eye(sz,codist) or C = eye(sz,datatype,codist) creates a codistributed identity matrix of the specified size and underlying class (the default datatype is 'double'). The codistributor object, codist, specifies the distribution scheme for creating the codistributed array. For information on constructing codistributor objects, see the reference pages for codistributor1d and codistributor2dbc. To use the default distribution scheme, you can specify a codistributor constructor without arguments. For example:

spmd
    C = eye(8,codistributor1d());
end

C = eye(sz,___,codist,'noCommunication') specifies that no interworker communication is to be performed when constructing a codistributed array, skipping some error checking steps.

C = eye(sz,___,codist,'like',P) creates a codistributed identity matrix with the specified size, underlying class (datatype), and distribution scheme. If either the datatype or codistributor argument is omitted, the characteristic is acquired from the codistributed array P.

Examples

Create Distributed Identity Matrix

Create a 1000-by-1000 distributed identity matrix of underlying class double:

D = eye(1000,'distributed');

Create Codistributed Identity Matrix

Create a 1000-by-1000 codistributed double identity matrix, distributed by its second dimension (columns). 

spmd(4)
    C = eye(1000,'codistributed');
end

With four workers, each worker contains a 1000-by-250 local piece of C.

Create a 1000-by-1000 codistributed uint16 identity matrix , distributed by its columns. 

spmd(4)
    codist = codistributor('1d',2,100*[1:numlabs]);
    C = eye(1000,1000,'uint16',codist);
end

Each worker contains a 100-by-labindex local piece of C.

Create gpuArray Identity Matrix

Create a 1000-by-1000 gpuArray identity matrix of underlying class uint32:

G = eye(1000,'uint32','gpuArray');

See Also

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Introduced in R2006b

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