I'm new to the IBM Q Experience. In the Composer, I built a circuit consisting of two Hadamard Gates and an Ry:
OPENQASM 2.0;
include "qelib1.inc";
qreg q[5];
creg c[5];
h q[0];
h q[0];
ry(pi/2) q[0];
measure q[0] -> c[0];
The results returned are 50/50 probability. However, when I apply the matrices in a spreadsheet, I get a $\frac{28}{72}$ result. (See image below.) For the Hadamard matrices, I'm using one divided by the square root of two for the corresponding a, b, and c elements and minus one divided by the square root of two for the d element. For the Ry matrix elements a,b c, and d, I have $\cos\big(\frac{pi/2}{2}\big)$, $-\sin\big(\frac{pi/2}{2}\big)$, $\sin\big(\frac{pi/2}{2}\big)$ and $\cos\big(\frac{pi/2}{2}\big)$, where $\pi=180^{\text{o}}$. The output squared in the spreadsheet gives me 28/72 probability. I hate to be a pest with such a low level question, but where in the matrices am I going wrong?
For $\pi$ I used 3.14 instead of 180 degrees, and it came out 50/50.