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Speed in calculators

In the last blog installment I was testing different calculations for amortization in different calculators, in particular several versions of the ubiquitous HP12c. This was due to a doubt on the accuracy - that ended up being dependent on the decimal setting, when preparing some tutorial for loan calculations with the HP12c

Most of the work was done on the newest HP12c. For all practical purposes and calculations, this HP12c is instantaneous. There is no waiting no matter the calculation. 

However, for comparison purposes I have also used the original HP12c. Then, the lag is evident on many calculations, in particular the ones that imply searching for a solution iteratively (like i for a TVM calculation, an IRR for a cashflow or a long amortization calculation. I used a 10 year amortization of a monthly loan, a total of 120 payments, and it took far more than 30 seconds to finish - what had been nearly instantaneous in the newer one.

To be fast costs energy - current processor consumptions depends on the megahertzs you apply to the machine. The firmware used in the newest ARM-based HP12c has different speeds for diffierent conditions. There is a no-calculation speed of 4 MHz; most of the keys' programs run at 12 MHz, and for the 5 TVM keys there is a special mode of 48 MHz. Here are i, IRR, AMORT, so it really goes fast here without draining batteries for lower complexity calculations. It goes fast where it is needed - and it shows. 

This week end we will show some comparisons between both.

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