# SOPA

Image via Wikipedia

For a long time, sitting on the side watching the internet play out. The latest news so far is that SOPA and PIPA have been withdrawn, will probably be re-written in some form and come back in another democratic cycle or so.

If I was US based, then I would take more personal steps in the war-on-copyright/fight-against-piracy. Alas, I’m not so I’m going to put up banners, say the right things and hold double standards on all matters.

I think I should finally weigh in here.

I think I have thought up a method of enforcing copyright that would make the RIAA, MPAA and other such organisations happy.

It just takes a bit of technical knowledge and some thought.

# Solution

Let us suppose we are given a set of linear equations $\mathbf{A}\mathbf{x}=\mathbf{b}$ to solve. Here $\mathbf{A}$ represents a square matrix of nth order and $\mathbf{x}$ and $\mathbf{b}$ vectors of $n$th order. We may either treat this problem as it stands and attempt to find $\mathbf{x}$, or we may solve the more general problem of finding the inverse of the matrix $\mathbf{A}$, and then allow it to operate on $\mathbf{b}$ giving the required solution or the equation as $\mathbf{x}=\mathbf{A^{-1}}\mathbf{b}$. If we are quite certain that we only require the solution to be the one set of equations, the former approach has the advantage of involving less work (about one-third the number of multiplications by almost all methods). If, however, we wish to solve a number of sets of equations with the same matrix $\mathbf{A}$ it is more convenient to work out the inverse and apply it to each of the vectors $\mathbf{b}$. This involves, in addition, $n^2$ multiplications and $n$ recordings for each vector, compared with a total of about $\frac{1}{3}n^3$ multiplications in an independent solution.

— Alan Turing (1948)

# bodmas

Image via Wikipedia

Here’s one doing the rounds on Facebook.

6/2(1+2)=?

Of course, the answer depends on how your year 7 skills at algebraic manipulations are.