# Variance

calculate the variance $\sigma^2= <\hat{O}^2>- <\hat{O}>^2$ of an operator $\hat{O}$

## Inputs

• $\hat{O}$: Operator - the operator to calculate the variance of
• $\psi$: state - the state the system is in when we want the variance

## Outputs

• Scalar: real number - the calculated variance

## Content

For convenience, the node displays its result directly