How do you install and use Theano?

Here is how to install and use Theano, a Python library for mathematical expression computation, especially useful for deep learning tasks.

1. Install dependencies: First, make sure you have Python and NumPy installed. If not, you can download and install them from the official website.
2. To install Theano: You can easily install Theano using the pip command. Just open your terminal or command prompt and type in the following command:
3. Install theano using pip.
4. Configure Theano: After installation, it is necessary to configure Theano to fully utilize the system’s performance. Create a file named .theanorc in the user directory and add the following content to the file.
5. [global]
   floatX = 32-bit floating point
   device = CPU

   [blas]
   ldflags = -lopenblas

6. If your system supports GPU computing, you can set the device to GPU and make any other necessary configurations accordingly.
7. With Theano, you can import the library into your Python script and start using it. Here is a simple example:
8. import theano
   import theano.tensor as T

   # Creating symbolic variables
   x = T.scalar(‘x’)
   y = T.scalar(‘y’)

   # Defining the mathematical expression
   z = x + y

   # Compiling the function
   add = theano.function([x, y], z)

   # Calling the function
   result = add(2, 3)
   print(result) # Output: 5

9. This example demonstrates how to create symbolic variables, define mathematical expressions, and perform calculations using Theano.

The above are installation and usage instructions for Theano. In practice, more complex neural network models can be built using Theano, and its automatic differentiation feature can be utilized for model training and inference.