In [1]:

```
import math as m
import numpy as np
import matplotlib.pyplot as plt
```

Write a function `least_squares(d)`

which takes as input a dictionary `d`

mapping floats to floats. The dictionary represents some finite collection of data points `(x, y)`

given by those pairs for which `d[x]=y`

. The function `least_squares(d)`

should return a pair `(a, b)`

determining a function of the form
$$f(x) = a \cos(x) + b \sin(x),$$
which minimizes the $\ell^2$-distance from `d`

:
$$\text{dist}(f,d) = \sqrt{ \sum_{y=d[x]} \big(f(x)-y\big)^2}.$$

In [ ]:

```
```