# A/B = c. Given c, derive A & B knowing (only) that they are both integers.

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Posted (edited)
50 minutes ago, uncool said:

What fractions do you expect?

No "Expectations". I get what the FEA produces.

50 minutes ago, uncool said:

How small is "relatively small" for numerator and denominator?

Once it gets beyond the 7th harmonic, their effect on the total equation (be it torque, power or efficiency losses) becomes marginal.

For an extreme upper limit of physical rpm, say 400, that equates to an upper limit of 1.68e5.

If the harmonics are electrical degrees related, it could be 3x higher.

Edited by Browseruk

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On 12/31/2019 at 12:37 AM, moth said:

then hopefully you can do prime factorization quickly

1020/1000
2 * 510 / 2 * 500
2 * 255 / 2 * 250
5 *51 / 2 * 125
/ 5 * 25
/ 5 * 5
51/50=1.02

You shouldn't have the decimal point in the numerator of that last fraction.

Both 2105263157894736842105263157895 and 100000000000000000000000000000000 are divisible by 5 since the first ends in "5" and the second ends in 0.  The first is 5 times 2105263157894736842105263157895 and the second is 5 times 20000000000000000000000000000000.  Again those are both multiples of 5.  The first of the two original numbers is 25 times 421052631578947368421052631579 and the second is 25 times 4000000000000000000000000000000.

Unfortunately, the first of those two numbers does not end in 5 or 0 so is not divisible by 5.  Since it is odd it is not divisible by 2. At this time we can pretty much stop.  Since 4000000000000000000000000000000= 4(10^30)= 2^2(2^30 5^30)= 2^(32)5^30.  The reduction to lowest terms of that fraction is 421052631578947368421052631579/4000000000000000000000000000000.

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I was joking about doing an infinite number of steps in a finite amount of time because the number is a repeating decimal with a rounding error. or is it?

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