# Wiki

Clone wiki# blaze / Bitwise Shift

## Vector/Vector Shift

Via the left-shift operator (i.e. `operator<<()`

) and the right-shift operator (i.e. `operator>>()`

) it is possible to perform an elementwise shift of a dense vector:

```
blaze::DynamicVector<unsigned int> v1( 5UL ), v3;
blaze::DynamicVector<unsigned short> v2( 5UL );
// ... Initializing the vectors
v3 = v1 << v2; // Elementwise left-shift of a dense column vector
v3 = v1 >> v2; // Elementwise right-shift of a dense column vector
```

Note that it is necessary that both operands have exactly the same dimensions. Violating this precondition results in an exception. Also note that it is only possible to shift vectors with the same transpose flag:

```
using blaze::columnVector;
using blaze::rowVector;
blaze::DynamicVector<unsigned int,columnVector> v1( 5UL );
blaze::DynamicVector<unsigned int,rowVector> v2( 5UL );
v1 << v2; // Compilation error: Cannot shift a column vector by a row vector
v1 << trans( v2 ); // OK: Shifting a column vector by another column vector
```

Furthermore, it is possible to use different element types in the two vector operands, but shifting two vectors with the same element type is favorable due to possible vectorization of the operation:

```
blaze::DynamicVector<unsigned int> v1( 100UL ), v2( 100UL ), v3;
// ... Initialization of the vectors
v3 = v1 << v2; // Vectorized left-shift of an unsigned int vector
```

## Matrix/Matrix Shift

The left-shift operator (i.e. `operator<<()`

) and the right-shift operator (i.e. `operator>>()`

) can also be used to perform an elementwise shift of a dense matrix:

```
using blaze::rowMajor;
using blaze::columnMajor;
blaze::DynamicMatrix<unsigned int,columnMajor> M1( 7UL, 3UL );
blaze::DynamicMatrix<unsigned short,rowMajor> M2( 7UL, 3UL ), M3;
// ... Initializing the matrices
M3 = M1 << M2; // Elementwise left-shift of a dense column-major matrix
M3 = M1 >> M2; // Elementwise right-shift of a dense column-major matrix
```

Note that it is necessary that both operands have exactly the same dimensions. Violating this precondition results in an exception. It is possible to use any combination of row-major and column-major matrices. Note however that in favor of performance using two matrices with the same storage order is favorable. The same argument holds for the element type: While it is possible to use matrices with different element type, using two matrices with the same element type potentially leads to better performance due to vectorization of the operation.

```
blaze::DynamicMatrix<unsigned int> M1( 50UL, 70UL ), M2( 50UL, 70UL ), M3;
// ... Initialization of the matrices
M3 = M1 << M2; // Vectorized left-shift of an unsigned int matrix
```

## Scalar Shift

It is also possible to uniformly shift all elements of a dense vector or dense matrix by means of a scalar, which has the same effect as shifting by means of a uniform vector or matrix (see `UniformVector`

and `UniformMatrix`

). In **Blaze** it is possible to use all built-in/fundamental data types except bool as scalar values. Examples:

```
blaze::DynamicVector<unsigned int> v1{ 3, 2, 5, 4, 1, 6 };
// Uniform left-shift by one bit of all elements of v1; Results in
//
// ( 6, 4, 10, 8, 2, 12 )
//
blaze::DynamicVector<int> v2( v1 << 1U );
```

```
blaze::DynamicMatrix<unsigned int> M1{ { 3, 2, 5 },
{ 4, 1, 6 } };
// Uniform left-shift by one bit of all elements of M1; Results in
//
// ( 6, 4, 10 )
// ( 8, 2, 12 )
//
blaze::DynamicMatrix<unsigned int> M2( M1 << 1U );
```

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