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What calculator do you use ?
slateraptor:
--- Quote from: ejeffrey on April 23, 2012, 01:13:55 pm ---So financial calculations must be done either with integers (representing cents), or decimal (BCD) representations.
--- End quote ---
Learn something new everyday. I suppose that would explain the BCD-encoded registers in older HP CPU architectures.
Are there any handheld calculators that actually use double-precision floats?
EDIT: Evidently, a few Sharp querty handhelds fit the bill...doesn't seem to be many without diving into the user-space realm.
saturation:
Sometimes from metrology labs, 'estimates' could refer to uncertainty in the LSD presented, not so much from the calculation, but the actual measurements 99.99% confidence interval, and thus estimates are good only to so many digits.
--- Quote from: slateraptor on April 23, 2012, 01:11:00 pm ---I hope you'll excuse me for raising an eyebrow when a NIST engineer speaks of numerical "estimates". :P
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Rounding errors make more sense, I stand corrected. However, if more digits were used in the calculation the rounding error can be masked, once rounded to a penny, but that may be too much to expect of lower cost hand held calculator.
For example, for financial transactions try this simple mortgage table:
200000 (1 + 0.06/360)^(360*30)
Casio scientifics have a small rounding issue, as seen in the FX260 and other models, it returns 1209747.95.
The right answer is 1209748.04, which can be done with higher precision calculators or better rounding.
Not a big deal for 9c difference, unless your a hacker stealing 9c from millions of accounts ;)
--- Quote from: ejeffrey on April 23, 2012, 01:13:55 pm ---
--- Quote from: saturation on April 23, 2012, 12:21:50 pm ---Even in the simplest use, debt or mortgage calculations, actual results by banks use very high precision numbers, 2-30x more than a general scientific calculator.
--- End quote ---
This is actually a myth propagated by financial types who don't understand math. Financial transactions are rounded to the nearest penny, and intermediate values in a financial calculation will be rounded aggressively at every step along the way. ...
--- End quote ---
baljemmett:
--- Quote from: saturation on April 23, 2012, 03:54:58 pm ---For example, for financial transactions try this simple mortgage table:
200000 (1 + 0.06/360)^(360*30)
Casio scientifics have a small rounding issue, as seen in the FX260 and other models, it returns 1209747.95.
The right answer is 1209748.04, which can be done with higher precision calculators or better rounding.
--- End quote ---
Interesting -- the Casios have obviously gone backwards sometime since the mid-80s/early-90s, then! Just tried that on my fx-7000GB and got 1209748.042; doing it in Fix2 mode also gives 1209748.04.
0xdeadbeef:
To be precise, my own calculator based on rational numbers says the answer is
1209748.03722963021023976099764994429324362344006195944401452964332492379118987483444215101643363697513166243909463144784174311993772628
:)
Lawsen:
This depends upon what type of mathematics you are doing and how small you want it. It is a complicated question, because there are so many options and choices that were not available a few years ago. You could have a complete calculator with an app software for an I Pod touch or I pad or Android telephone or tablet. I use a Casio fx-10cg (20cg outside of North America. It is a back lit color LCD display graphing calculator, very large. On the small is a common solar cell TI-30sx, just numerics. I have an HP Kinpo made HP-49G+. I like the color one more. I have an old TI-92 with the Motorola 68000 CMOS processor inside it. It is an 16 years old math ship, too big to be a calculator. I like the TI Nspire CAS CX in color, but I already have a color Casio, so no need.
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