How Computers Think
A good reminder of what happens when we become careless with technology. I needed to convert temperature from degrees Celsius to degrees Fahrenheit. Out comes the trusty TI-85 calculator. Bring up the conversion menu, and into the temperature subsection. I entered my conversion:
-30 C > F
and get back -86. Almost subconsciously, this answer struck me as incorrect. A sanity check with a co-worker confirmed my suspicion that it was indeed incorrect. What was going on? After pondering, I tried the conversion again in a slightly different manner:
(-30) C > F
this time getting back -22. A quick check using the conversion formula itself:
TF=9⁄5*TC+32
verified the answer:
TF=9⁄5*(-30)+32=-22
So what happened? It turns out that in the first attempt, my trusty TI was really doing this:
-1*(30 C > F)
TI should warn users about this. Maybe they do. It has been a long time since I opened that user manual. I wonder how this works on RPN-style calculators? Or if this behavior is corrected or accounted for on the newer models like the TI-86?