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Collector
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Re: Stupid question of the day

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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katastrofa
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Re: Stupid question of the day

January 10th, 2019, 5:53 pm

Why Mona Lisa doesn't have eyebrows?
 
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Cuchulainn
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Re: Stupid question of the day

January 10th, 2019, 7:35 pm

Why Mona Lisa doesn't have eyebrows?
The project went over-budget. Those old-timers knew their project management.
Or maybe Leonardo lost interest and started on his helicopter.

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ppauper
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Re: Stupid question of the day

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.
 
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katastrofa
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Re: Stupid question of the day

January 10th, 2019, 11:50 pm

So it is possible that she was Irish!
 
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Cuchulainn
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Re: Stupid question of the day

January 11th, 2019, 12:10 am

So it is possible that she was Irish!
I haven't seen many Irish women lately. When did it start?
 
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katastrofa
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Re: Stupid question of the day

January 11th, 2019, 12:11 am

Are you saying that Irish women aren't as hairy as Irish men?
 
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ppauper
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Re: Stupid question of the day

January 11th, 2019, 6:35 am

Are you saying that Irish women aren't as hairy as Irish men?
hey, it's januhairy
 
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katastrofa
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Re: Stupid question of the day

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.
 
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Cuchulainn
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Re: Stupid question of the day

January 15th, 2019, 7:46 am

Is eco-tourism destroying the planet?
 
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Collector
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Joined: August 21st, 2001, 12:37 pm

Re: Stupid question of the day

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?
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?
 
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FaridMoussaoui
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Re: Stupid question of the day

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))

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bearish
Posts: 4417
Joined: February 3rd, 2011, 2:19 pm

Re: Stupid question of the day

January 24th, 2019, 7:41 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?

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 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.
 
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bearish
Posts: 4417
Joined: February 3rd, 2011, 2:19 pm

Re: Stupid question of the day

January 24th, 2019, 7:42 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))

Image
It does work in Excel, although I think it would take me a little time to get comfortable with the notation.
 
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FaridMoussaoui
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Re: Stupid question of the day

January 24th, 2019, 8:07 pm

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