I am wondering about The Old Mystical Formula, if it truly make sense? is it sound mathematical and logical?

- katastrofa
**Posts:**7660**Joined:****Location:**Alpha Centauri

Why Mona Lisa doesn't have eyebrows?

- Cuchulainn
**Posts:**59024**Joined:****Location:**Amsterdam-
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The project went over-budget. Those old-timers knew their project management.Why Mona Lisa doesn't have eyebrows?

Or maybe Leonardo lost interest and started on his helicopter.

2007: Solved: Why Mona Lisa doesn't have eyebrows

His conclusion is that Mona Lisa once had both eyebrows and eyelashes, but that these have been gradually eroded to the point that they are no longer visible.

- katastrofa
**Posts:**7660**Joined:****Location:**Alpha Centauri

So it is possible that she was Irish!

- Cuchulainn
**Posts:**59024**Joined:****Location:**Amsterdam-
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I haven't seen many Irish women lately. When did it start?So it is possible that she was Irish!

- katastrofa
**Posts:**7660**Joined:****Location:**Alpha Centauri

Are you saying that Irish women aren't as hairy as Irish men?

hey, it's januhairyAre you saying that Irish women aren't as hairy as Irish men?

- katastrofa
**Posts:**7660**Joined:****Location:**Alpha Centauri

It's a pity it's not Augustink. I have to go out this evening I will have to take a shower (or maybe even a bath), not out of decency - out of mercy.

- Cuchulainn
**Posts:**59024**Joined:****Location:**Amsterdam-
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Is eco-tourism destroying the planet?

what algorithm is Excel using for taking x^y

assume x<0 and y between 0 and 1...is it then a bit strange excel gives output when y=0.2 (it should be a imaginary number, Mathematica get it right, but why is Excel giving error for all except y=0.2 ?) I would expect also error here?

likely very stupid question, but I was just wondering if Excel could do imaginary numbers, and it looks like it can do some, but with wrong answer. Am I imagining this?

assume x<0 and y between 0 and 1...is it then a bit strange excel gives output when y=0.2 (it should be a imaginary number, Mathematica get it right, but why is Excel giving error for all except y=0.2 ?) I would expect also error here?

likely very stupid question, but I was just wondering if Excel could do imaginary numbers, and it looks like it can do some, but with wrong answer. Am I imagining this?

- FaridMoussaoui
**Posts:**371**Joined:**

As there are many solutions, we should select one. I used the following formula for LibreOffice Calc (on Linux) but it should work with Excel. (IM is for complex functions and a^b is evaluated as exp(log(a)*b))

=IMEXP(IMPRODUCT(IMSUM(IMLN(-2),COMPLEX(0,0*PI())),0.3))

=IMEXP(IMPRODUCT(IMSUM(IMLN(-2),COMPLEX(0,0*PI())),0.3))

It works because a negative number has a unique real 5th root. Same thing if you raise it to the reciprocal of any odd integer. The exact process in which Excel casts the variant 0.2 to the reciprocal of the integer 5 is murky to me, but it seems to work in general.what algorithm is Excel using for taking x^y

assume x<0 and y between 0 and 1...is it then a bit strange excel gives output when y=0.2 (it should be a imaginary number, Mathematica get it right, but why is Excel giving error for all except y=0.2 ?) I would expect also error here?

Screen Shot 2019-01-24 at 4.36.58 PM.png

likely very stupid question, but I was just wondering if Excel could do imaginary numbers, and it looks like it can do some, but with wrong answer. Am I imagining this?

It does work in Excel, although I think it would take me a little time to get comfortable with the notation.As there are many solutions, we should select one. I used the following formula for LibreOffice Calc (on Linux) but it should work with Excel. (IM is for complex functions and a^b is evaluated as exp(log(a)*b))

=IMEXP(IMPRODUCT(IMSUM(IMLN(-2),COMPLEX(0,0*PI())),0.3))

- FaridMoussaoui
**Posts:**371**Joined:**

I found those formulas in a forum around 2010. Unfortunalely, I didn't save the link.

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