> ## Documentation Index
> Fetch the complete documentation index at: https://docs.qbraid.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Usage Examples

## Key Features: Load algorithms as PyQASM modules and QASM files

qBraid Algorithms provides a collection of quantum algorithms that can be loaded
as [PyQASM](/v2/pyqasm/user-guide/overview) modules, or
you can generate .qasm files to use them as subroutines in your own circuits.

### Loading Algorithms as PyQASM Modules

To load an algorithm as a [PyQASM module](/v2/pyqasm/user-guide/overview#the-qasmmodule-object), use the `load_algorithm` function from the `qbraid_algorithms` package, passing algorithm-specific parameters. For example, to load the Quantum Fourier Transform (QFT) algorithm:

```python theme={null}
from qbraid_algorithms import qft

qft_module = qft.load_algorithm(3) # Load QFT for 3 qubits
```

Now, you can perform operations with the PyQASM module, such as [unrolling](/v2/pyqasm/user-guide/examples#inlining-and-unrolling), and
converting back to a QASM string:

```python theme={null}
qft_module.unroll()
qasm_str = pyqasm.dumps(qft_module)
```

### Loading Algorithms as `.qasm` Files

In order to utilize algorithms as subroutines in your own circuits, use the
`generate_subroutine` function for your desired algorithm. By passing algorithm-specific parameters, and optionally a desired output path, you can
generate a .qasm file containing a subroutine for the parameterized circuit. For
example, to generate a QFT subroutine for 4 qubits:

```python theme={null}
from qbraid_algorithms import qft, iqft
path = "path/to/output" # Specify your desired output path
qft.generate_subroutine(4) # Generate 4-qubit QFT in the current directory
iqft.generate_subroutine(4, path=path) # Generate 4-qubit IQFT in specified path

```

To utilize the generated subroutine in your own circuit, include the generated
.qasm file, and call the subroutine on an qubit register of the size specified
when generating the subroutine. For example, after running

```python theme={null}
qft.generate_subroutine(4)
```

you can append `include "qft.qasm";` to your OpenQASM file, and call the
subroutine. For example:

```qasm theme={null}
OPENQASM 3.0;
include "qft.qasm";

qubit[4] q;
bit[4] c;

qft(q);
measure q -> c;
```