# OfficeOne 894 Graphic Calculator

Ok, so, it cost AUD \$7, but it looks like you get what you pay for.

### Bug 1

Tripped over this when calculating the bond angle in methane, the tetrahedral angle. First, in calculator-like format, with the calculators response at the end:

• Deg:2tan-1√2 = 109.4712206
• Deg:90 + sin-1(3-1) = 109.4712206
• Deg:90 + sin-1(3-1) - 2tan-1√2 = 2e-09
• Deg:sin-1(3-1) + 90 - 2tan-1√2 = 2e-09
• Deg:2tan-1√2 - 90 - sin-1(3-1) = 19.13138372 huh?

Those last three lines should be approximately zero, since $2\cdot\arctan \sqrt{2} = 90 + \arcsin \tfrac{1}{3}$ but no matter how many parenthesis I put in, that last line refuses to work. Interestingly, switching to radians makes it work:

• Rad:2tan-1√2 - Π÷2 - sin-1(3-1) = -2.4e-11

### Bug 2

The random number generator is fine when running interactively, but when run in a tight loop, values tend toward 0 or 1.

Scl:-1000→A:Lbl 0:Ran# dt :Isz A:Goto 0

Let's have a look at some of the statistics variables:

• $n = 1000$
• $\sum{x} = 598$
• $\sum{x^2} = 357.604$
• $\bar x = 0.598$
• $x\sigma _{n-1} = 0$

Ok, that's unexpected.

Misinformation found herein copyright Paul Ripke (aka “stix”) stixpjr@gmail.com.