Math Is Fun Forum

  Discussion about math, puzzles, games and fun.   Useful symbols: ÷ × ½ √ ∞ ≠ ≤ ≥ ≈ ⇒ ± ∈ Δ θ ∴ ∑ ∫ • π ƒ -¹ ² ³ °

You are not logged in.

#26 Re: Help Me ! » Curve Fitting » 2010-08-26 22:08:11

Hi Bobby

It's nothing actually recorded, and the set is not big (only 5 elements). I was just trying to see how I could put what I am learning into some practice.

The set is this

Time(t)    Fluid(F)
0             0
1             3
2             10
3             12
4             15
5             18

I can do plots and regression lines and also find gradients between the elements, but not sure how I would go about creating something that would smoothly pass through them as a function of (t)

Also my MATLAB has stopped working, so trying to fix that at the moment.

#27 Help Me ! » Curve Fitting » 2010-08-26 21:15:08

DaveRobinsonUK
Replies: 13

If I have some data and I do a scatter plot of the data.

How could I produce a function which plots a line through the data points?

Would it have to be piecewise, between the points or could you have one function and some algorithm to do this?

#28 Re: Help Me ! » Naturual Logarithms » 2010-08-23 01:52:43

ok so its a reflection in the line y=x

#29 Re: Help Me ! » Naturual Logarithms » 2010-08-23 01:27:06

I think i see now.

So ln is the reciprocal of e^x.

Here's hoping.

#30 Re: Help Me ! » Naturual Logarithms » 2010-08-23 01:01:00

hi guys.

Sorry I had to nip out to feed the toddler some lunch, and also to do a bit of backtracking through the books
back now

smile

#31 Re: Help Me ! » Naturual Logarithms » 2010-08-23 00:15:18

just to clarify

so when you say raise to e^x

does this mean

#32 Re: Help Me ! » Naturual Logarithms » 2010-08-22 23:49:46

All is ok here,apart from our neighbors are rowing periodically at the moment. 11PM they were at it last night, sounded like they were throwing pans and plates at each other. Maybe there is someway to calculate when this is going to happen. Then we can arrange to be out. smile

O.k

so I move ln(x-1) to the right giving



take both sides to e^x

not sure how to get

from that

Feel like I have gone backwards at the moment, do you ever get that?

#33 Re: Help Me ! » Naturual Logarithms » 2010-08-22 23:33:58

Hi Bobby.. Hows things pal?
and hello Bob Bundy, thank you for the help.

I got the first one. Though I am still stuck on the next, and the one after that seems to be similar if opposite.

I have done this, though the answer should be

using first law of logs

though I know this can't be right because raising by e^x, just gives the factors given to start with.

#34 Help Me ! » Naturual Logarithms » 2010-08-22 22:36:11

DaveRobinsonUK
Replies: 105

Hi All

I have been stuck on this for a few days now, and seem to be getting more and more perplexed.

It was all going well, and then I hit a few questions that I don't know how to do and can't seem to
find an explanation. Or maybe I have seen it and then forgotten that it applies in this case.

The questions are of the form

Solve:

I am also not seeing how the identities

and
work.

Is

the same as
based on

Quite confused!

Thank you

#35 Re: Help Me ! » Could use some help with Derivatives of e^kx » 2010-08-17 01:34:55

Hi Bob

yes sorry, the missing k is a typo on my part.

Thank you for the help, that has cleared things up for me.

Cheers
Dave

#36 Help Me ! » Could use some help with Derivatives of e^kx » 2010-08-15 23:08:43

DaveRobinsonUK
Replies: 3

Hi All.

I am trying to make my way through the definition for the derivative of

I can follow it fine until this part.

the next part has got me

i am not following how the k is taken out, it just seems to appear? The the k on the numerator is taken out of the fraction to give.

Should I review first principals before continuing?

Thanks

Dave

#37 Dark Discussions at Cafe Infinity » Very General » 2010-08-07 08:07:04

DaveRobinsonUK
Replies: 3

Just something simple today

How is everybody?

Hope all is well and cool things are being learned  smile

#38 Re: Dark Discussions at Cafe Infinity » Where am I? » 2010-08-01 00:42:41

Wow, would love to be able to understand that. Maybe one day smile

I don't get it either, it's like every universe would be smaller in terms of matter than the preceding one, and also proportional to the mass of the star that created it.

#39 Dark Discussions at Cafe Infinity » Where am I? » 2010-07-30 19:56:27

DaveRobinsonUK
Replies: 4

What's up dude's smile

I was reading last weeks New Scientist the other day and came across this article, would like
to see what the gang thought of it.

Here is the link
http://www.newscientist.com/article/mg20727703.000-every-black-hole-may-hold-a-hidden-universe.html

I suppose it is an explanation for everything coming from a single point at the big bang. Does it mean that
each universe is made from one star? Or is everything else made from other stuff consumed during the course
of time after the hole is created?

mmmm hmm

#40 Re: Help Me ! » Improper Integrals » 2010-07-19 08:03:00

I just thought of something. I'm sure there is probably a way around it, though I haven't come across it yet.

What happens when you need to integrate

how do you get around the division by 0

#41 Re: Help Me ! » Improper Integrals » 2010-07-18 20:32:59

Hi Bobby

bobbym wrote:

Hi Dave;

No, I would do it like this:

Sorry about that, a typo.

Thank you for this.

#42 Re: Help Me ! » Improper Integrals » 2010-07-18 19:56:07

Hi Bobby

Nice one.. I'll give that a try, she has woken up in a funny mood and already been sent to her room once.

I've only watched the first one so far, and then had another go with the book. I think I have it, though I'm going to look at the rest to be sure.

Is it right that you choose

if the asymptote stretches out to

and

when stretching out to

and that the the area under the curve can only be found when the limit converges on 0, otherwise it is divergent and the area is NaN.

I don't know, maybe I am pushing too hard. I only read about these for the first time last thursday, and 10 months ago I couldn't even add two fractions.

Still I prefer to go on, I like it.:)

#43 Re: Help Me ! » Improper Integrals » 2010-07-18 05:51:40

Hi Bobby

Thanks for that, Emma has just been sent to her room for 10 mins for being a bad girl so I will watch some now.

smile

#44 Help Me ! » Improper Integrals » 2010-07-18 05:14:45

DaveRobinsonUK
Replies: 9

Are improper integrals Definite or Indefinite?

The AQA books I am working from are trying to describe it all in half a page, as is often the case.  My other book throws some more light, but still confusing.

It gives this as the first example..

Find

Determine the limit

I can understand why the limit would not exist due to x^2 non being a number and diverging.

I don't know.. I'm stuck.:/

#46 Re: Dark Discussions at Cafe Infinity » Planet Killer? » 2010-07-14 18:39:06

LQ wrote:

How does one usually do it?

They used to just get Red Adair in, but there is a problem with that.

a) It's a mile underwater.
b) He's Dead!

With any luck he's working on a building site in Woking with Elvis. They can both make a comeback and save the Earth. wink

#47 Re: Euler Avenue » Gurth's Fractals » 2010-07-13 08:30:51

Hi Gurth

At the moment i am doing my graphic stuff using Maya and the like, I want to get into programming my own graphics but I am still getting to grips with the maths behind it all and also need a language that is easier to do graphics on than C++. I see you use Delphi.

btw

Thank you for posting your code.

#48 Re: Dark Discussions at Cafe Infinity » The a-bombs possibly allready killed us through gravitational effects » 2010-07-13 06:57:30

Hi Bobby

He sort of shows a convection system of the earth's core with the fluid moving up through a central core and then falling round the sides of the sphere, in more or less the same shape as the magnetosphere itself. Though I may be wrong I just though of the old chestnut with the iron fillings on a piece of paper and the shape is the same, it may not be spherical but neither is a piece of paper.

I was reading about Einstein on the bus into Guildford before, I didn't know he was actually in favour of the A-bomb. We are always told he was benign and against, but then again all the advocates of that stance never show you the letter he wrote to Roosevelt. If you read between the lines he is saying that it is important to gain the knowledge before the Nazis do because they will use it if they have it.

#49 Re: Dark Discussions at Cafe Infinity » The a-bombs possibly allready killed us through gravitational effects » 2010-07-12 17:15:29

Hi Bobby

I must admit I am a long way off from anything that could be called a full understanding, at the moment I am reading this book called Atom, about the history of it all. Did they give it up for the Standard Model?

I didn't sleep well last night and was thinking about the Better Dynamo theory. Does it have to move like that, you still get the same sort of shape of magnetic field from a bar magnet and thats just piece of ferrous metal?

#50 Re: Dark Discussions at Cafe Infinity » The a-bombs possibly allready killed us through gravitational effects » 2010-07-12 03:59:26

Help!!!!

I think he gets a little hard to understand when he thinks sub atomic particles are behaving like planets and moons.

Wasn't the Copenhagen View that the structure of the atom could not be considered in such a form or indeed any form other than algebraic.

I quite like his Better Dynamo theory.

http://mb-soft.com/public/tecto2.html



Or is this a new thing?

Board footer

Powered by FluxBB