### Re: Stupid question of the day

Posted:

**January 8th, 2019, 10:34 pm**I am wondering about The Old Mystical Formula, if it truly make sense? is it sound mathematical and logical?

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Posted: **January 8th, 2019, 10:34 pm**

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

Posted: **January 10th, 2019, 5:53 pm**

Why Mona Lisa doesn't have eyebrows?

Posted: **January 10th, 2019, 7:35 pm**

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.

Posted: **January 10th, 2019, 8:40 pm**

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.

Posted: **January 10th, 2019, 11:50 pm**

So it is possible that she was Irish!

Posted: **January 11th, 2019, 12:10 am**

I haven't seen many Irish women lately. When did it start?So it is possible that she was Irish!

Posted: **January 11th, 2019, 12:11 am**

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

Posted: **January 11th, 2019, 6:35 am**

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

Posted: **January 11th, 2019, 6:44 am**

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.

Posted: **January 15th, 2019, 7:46 am**

Is eco-tourism destroying the planet?

Posted: **January 24th, 2019, 3:41 pm**

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?

Posted: **January 24th, 2019, 4:16 pm**

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))

Posted: **January 24th, 2019, 7:41 pm**

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?

Posted: **January 24th, 2019, 7:42 pm**

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))

Posted: **January 24th, 2019, 8:07 pm**

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