A1.1 Write a Python program to print `Hello World!'.
A1.2 Write a Python program that reads and inverts a string.
A1.3 Write a Python program to plot a multivariate Gaussian with a covariance matrix that has off-diagonal elements which are half the value of the on-diagonal elements.
A1.4 Write a Python program with a function that takes two arrays, a and b, and calculates the matrix a*b'**2 +b.
A1.5 Calculate the gradient of a two dimensional Gaussian and find the minimum.