# Operation Sides
> BLAS operation sides.
## Usage
```javascript
var operationSides = require( '@stdlib/blas/base/operation-sides' );
```
#### operationSides()
Returns a list of BLAS operation sides.
```javascript
var out = operationSides();
// e.g., returns [ 'left', 'right' ]
```
The output array contains the following types:
- `left`: a triangular matrix is on the left side of a matrix-matrix operation (e.g., AX = B, where A is a triangular matrix).
- `right`: a triangular matrix is on the right side of a matrix-matrix operation (e.g., XA = B, where A is a triangular matrix).
## Examples
```javascript
var contains = require( '@stdlib/array/base/assert/contains' ).factory;
var operationSides = require( '@stdlib/blas/base/operation-sides' );
var isOperationSide = contains( operationSides() );
var bool = isOperationSide( 'right' );
// returns true
bool = isOperationSide( 'left' );
// returns true
bool = isOperationSide( 'beep' );
// returns false
```
* * *
## C APIs
### Usage
```c
#include "stdlib/blas/base/operation_sides.h"
```
#### STDLIB_BLAS_OPERATION_SIDE
An enumeration of BLAS operation sides with the following fields:
- **STDLIB_BLAS_LEFT**: a triangular matrix is on the left side of a matrix-matrix operation (e.g., `XA = B`, where `A` is a triangular matrix).
- **STDLIB_BLAS_RIGHT**: a triangular matrix is on the right side of a matrix-matrix operation (e.g., `XA = B`, where `A` is a triangular matrix).
```c
#include "stdlib/blas/base/operation_sides.h"
const enum STDLIB_BLAS_OPERATION_SIDE v = STDLIB_BLAS_RIGHT;
```
### Notes
- Enumeration constants should be considered opaque values, and one should **not** rely on specific integer values.