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 November 15th, 2015, 03:53 AM #1 Member     Joined: May 2014 From: Rawalpindi, Punjab Posts: 69 Thanks: 5 Square root of -1 -1^0.5 = ? if the answer is -1^0.5 = i then the question is what is i as far as I recall my number system, I see only numerals and no letters
November 15th, 2015, 04:17 AM   #2
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Quote:
 Originally Posted by AbrahamA what is i ...
It is the imaginary unit.

 November 15th, 2015, 04:17 AM #3 Math Team   Joined: Dec 2013 From: Colombia Posts: 7,664 Thanks: 2644 Math Focus: Mainly analysis and algebra So in your number system there is no square root of -1. Please don't post threads that are likely to confuse people who are genuinely interested in learning some mathematics.
 November 15th, 2015, 04:38 AM #4 Global Moderator     Joined: Oct 2008 From: London, Ontario, Canada - The Forest City Posts: 7,948 Thanks: 1139 Math Focus: Elementary mathematics and beyond Where's the point of confusion? Last edited by greg1313; November 15th, 2015 at 04:52 AM.
November 15th, 2015, 04:47 AM   #5
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Quote:
 Originally Posted by v8archie Please don't post threads that are likely to confuse people who are genuinely interested in learning some mathematics.
I too am interested in learning some mathematics

Please tell me the value of ln(0) that is the natural log of zero

November 15th, 2015, 04:48 AM   #6
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Quote:
 Originally Posted by greg1313 It is the imaginary unit.
Thank you, for a second I thought it was my friend/mentor named Rush H Limbaugh III whose first named was scribbled on that wall in your Avatar

 November 15th, 2015, 04:49 AM #7 Math Team   Joined: Dec 2013 From: Colombia Posts: 7,664 Thanks: 2644 Math Focus: Mainly analysis and algebra The logarithm is not defined at zero, as I suspect you know.
 November 15th, 2015, 04:52 AM #8 Global Moderator     Joined: Oct 2008 From: London, Ontario, Canada - The Forest City Posts: 7,948 Thanks: 1139 Math Focus: Elementary mathematics and beyond Please post separate questions in separate threads. log(0) is undefined. Now please return to your original question (what is "i").
November 15th, 2015, 05:03 AM   #9
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Quote:
 Originally Posted by AbrahamA then the question is what is i
It is simple convention,

no more than that ...

It is a convenient convention,

to develop a comprehensive theory,

but even just for now ...

November 15th, 2015, 06:11 AM   #10
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Quote:
 Originally Posted by greg1313 Please post separate questions in separate threads. log(0) is undefined. Now please return to your original question (what is "i").
I am a formulator.

My job is akin to creating moulds that takes raw material and turns it into finished products.

If I was given a mould for division that takes two operands and in theory the mould should produce a finished product regardless of the values of two operands.

Same holds true for Square root of a number, in my case the mould is the Sqrt(x) function. Thus in theory this mould called Sqrt should produce a finished product regardless of the value of its operand.

Further log(x) is another mould, it too should produce a finished product regardless of the value of its operand.

Unless me too dumb to be told that the moulds have a defect and they are certain values for which it is unable to product finished products.

In past I was given a mould that produced finished products as internal rate of return with the raw material being N cash flows. The pundits believed that such moulds too were defective as there was no such single mould that could churn out finished products given any number of cash flows higher than 5. Even with cash flow below five, they required separate moulds whereas my mould was unique it worked for any number of cashflows and produced a single finished product rather than a set of useless product out of which only one had any use.

Field of mathematics is not static in time, the theories presented by creators of Calculus may or may not hold true in future.

For example, tangent of 90 degrees may get defined yet at present it is left undefined

Same goes for ln(0) natural log of zero

I am not a mathematician, for that matter I only have taught myself financial mathematics in the last 9 years and put together 1000 finance formulas books where a single function integrates a large number of unique functions. In the current series I arrived at the limit of the single function that integrates an infinite number of unique functions.

Almost all textbooks on Financial Management at most contain 10 time value of money functions whereas my books start with 1,700 functions in the first book and the 6th book it gets to infinite functions.

So why should I bother learning from a business school such as Wharton, Yale, MIT or Stanford when I know much more being confined to rural Punjab in South Asia?

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