Math and Excel Question (nerd content)

[pmann]

I know there are some fellow nerds here as I have seen you in the Math thread. I have a question that I am not easily finding the answer to.

It is possible to plot non-linear equations in Excel? Like, on a graph? It's logarithmic in nature, not just mx+b. I suppose I can do a scatter chart.

I can post the equation in a bit but it's long and cumbersome.

I thought I'd ask here because I know there are some math brains in our midst. No one here at work can figure it and I'm not an Excel wizard with graphs.

Thanks in advance and I'll post the equation shortly. I realize this is a long shot.

[pmann]

Oh, and can it plot the actual equation?

[DrHappy]

I'm only aware of adding a trend line for existing data points. You right click on one of the data points one the chart, and select the Trend/Regression type. I suppose you could define a trend line, and then change the data points to something that would be invisible.

[pmann]

My calculator doesn't even like the equation. It has a hard time plotting it and it is a pretty powerful calculator. Excel, from what I see so far is only able to plot data points. It looks like I'm going to have to pick sample points and plot them. It seems like Excel should be able to plot a two variable system. I don't understand why it can't. I really don't. I can see it having trouble with my particular problem, as it's logarithmic.

Here is the equation:



The unknowns are t and Ibf (that is one variable). I have the letter E in there, but I define that as it changes for my different scenarios. And the log is actually log base 10, not ln (natural log). It's a bitch figuring out how to represent that in Excel.

Thanks for the idea Dr. I'll see what I can get.

And sorry about such an off the wall question. But a lot of people come to this site, so I figure we may have some expertise.

[Primalex]

Excel is a spreadsheet software.

Trying to do this with Excel is like trying to write a letter with MS Paint. Why would you want this?

Use MatLab for this.

[pmann]

Originally Posted by Primalex

Excel is a spreadsheet software.

Trying to do this with Excel is like trying to write a letter with MS Paint. Why would you want this?

Use MatLab for this.

I understand. But I do not have Matlab or Mathcad at my fingertips. My old laptop has both, but that thing ate shit long ago.

All I want is a simple plot of the equations. I thought maybe Excel would do this.

But you recommend Paint, huh? As you see, I'm a master of paint.

[Primalex]

Originally Posted by pmann

I understand. But I do not have Matlab or Mathcad at my fingertips.

Then use Mathematica.

http://www.wolframalpha.com

uses this as engine for equations (no surprise, it's from the same person).

http://www.wolframalpha.com/examples/Math.html

[IrisAlthea]

Originally Posted by Primalex

Then use Mathematica.

http://www.wolframalpha.com

uses this as engine for equations (no surprise, it's from the same person).

http://www.wolframalpha.com/examples/Math.html

And it works on the iPad.
Thank you so much for the link!

[pmann]

Originally Posted by Primalex

Then use Mathematica.

http://www.wolframalpha.com

uses this as engine for equations (no surprise, it's from the same person).

http://www.wolframalpha.com/examples/Math.html

Thank you for this!!! It looks amazing!!!

[Bramblethorn]

Originally Posted by pmann

My calculator doesn't even like the equation. It has a hard time plotting it and it is a pretty powerful calculator. Excel, from what I see so far is only able to plot data points. It looks like I'm going to have to pick sample points and plot them. It seems like Excel should be able to plot a two variable system. I don't understand why it can't. I really don't. I can see it having trouble with my particular problem, as it's logarithmic.

Here is the equation:



The unknowns are t and Ibf (that is one variable). I have the letter E in there, but I define that as it changes for my different scenarios. And the log is actually log base 10, not ln (natural log). It's a bitch figuring out how to represent that in Excel.

If you want to plot a function in base Excel you'll probably need to generate pairs of points, then do an x-y plot and select one of the "connect points with lines" options. However, this addon appears to do what you're after and there's an alternate method here. (Disclaimer: haven't used these myself and can't vouch for them.)

In Excel "Log(x)" will give you the base-ten log of x, "Log(x,y)" will give the base-y log, and "Ln(x)" will give the natural log.

Looking at your equation, you can simplify it further by remembering that log(10^blah) = blah.

[pmann]

I was able to get a smooth line plot using the x-y scatter option. I didn't actually plot the equation, but rather a shitload of points in the graph. It's not perfect, but it works well enough. Until I get a chance to look at that other website that Primalex posted. That looks like a powerful tool. (That's what she said)

This Excel sheet will work well enough for upper management types who don't understand this stuff anyway.

[Rainshine]

Don't worry about it, the answer is always 7.

[GiggLeGasm]

Originally Posted by Rainshine

Don't worry about it, the answer is always 7.

lol.. our go-to answer was always 6..
took me back.. made me laugh. thanks

[Rainshine]

Originally Posted by GiggLeGasm

lol.. our go-to answer was always 6..
took me back.. made me laugh. thanks

lol Gosh I hated Maths. Especially those questions about trains leaving stations... man...

[pmann]

Originally Posted by Rainshine

lol Gosh I hated Maths. Especially those questions about trains leaving stations... man...

I like how you call it Maths *laughs*.

The train questions weren't interesting. Perhaps if we knew why the train was leaving the station.

"A train full of Playboy models leaves to meet the needs of Hugh Jackman and Christian Bale..."

See? Already more interesting.

[Rainshine]

I like how you call it interesting. *laughs*

Oh wait, no I don't!

[Emerson40]

Originally Posted by pmann

I like how you call it Maths *laughs*.

The train questions weren't interesting. Perhaps if we knew why the train was leaving the station.

"A train full of Playboy models leaves to meet the needs of Hugh Jackman and Christian Bale..."

See? Already more interesting.

<<== Foot tappin' stuff, when waiting for a train or finding square roots. You don't always have to show your work

[dougsan]

Math is always beautiful. It is the language of logic. Not that I'm a math freak, just a lover of math who does math problems to while away the hours.

Excellent job on the previous.

Don't you love Excel? I worked on digicalc too many years ago. For those who wonder, digicalc was the precurser to Lotus 123, which was the precursor to Excel.

It is my believe Microsoft borrowed a lot of the S/W they claimed ownership to over the years. Some they paid well for some they may not have.

Love the old days. Anyone remember punched card programming?

[stickygirl]

Psst... got a punch-card porn? I'd love to see some photos - y'know the real vintage B/W stuff. We have a PC in the lab that has orange lettering!!

[DvorakAgain]

Originally Posted by pmann

My calculator doesn't even like the equation. It has a hard time plotting it and it is a pretty powerful calculator. Excel, from what I see so far is only able to plot data points. It looks like I'm going to have to pick sample points and plot them. It seems like Excel should be able to plot a two variable system. I don't understand why it can't. I really don't. I can see it having trouble with my particular problem, as it's logarithmic.

Here is the equation:



The unknowns are t and Ibf (that is one variable). I have the letter E in there, but I define that as it changes for my different scenarios. And the log is actually log base 10, not ln (natural log). It's a bitch figuring out how to represent that in Excel.

Thanks for the idea Dr. I'll see what I can get.

And sorry about such an off the wall question. But a lot of people come to this site, so I figure we may have some expertise.

Is that the equation for arc flash energy?

[pmann]

Originally Posted by DvorakAgain

Is that the equation for arc flash energy?

Yes. But there was an error in that. I can't remember where, but I think I did the log incorrectly. It's fixed. And I just, instead of plotting the actual equation, plotted a shitload of points.

Is there another nerd among us???

[BeachMomma]

Originally Posted by pmann

My calculator doesn't even like the equation. It has a hard time plotting it and it is a pretty powerful calculator. Excel, from what I see so far is only able to plot data points. It looks like I'm going to have to pick sample points and plot them. It seems like Excel should be able to plot a two variable system. I don't understand why it can't. I really don't. I can see it having trouble with my particular problem, as it's logarithmic.

Here is the equation:



The unknowns are t and Ibf (that is one variable). I have the letter E in there, but I define that as it changes for my different scenarios. And the log is actually log base 10, not ln (natural log). It's a bitch figuring out how to represent that in Excel.

Thanks for the idea Dr. I'll see what I can get.

And sorry about such an off the wall question. But a lot of people come to this site, so I figure we may have some expertise.

*eyes glazed over*

Train questions are easy. It doesn't matter what time they'll collide; there's going to be a lot of dead people and one hell of a mess to clean up.

Oh, I beg to differ, but the answer is always 49.

[babyoillover]

Surely the answer is always 42!

[FHMbabe]

Look at that writing!!! (0_0)

[pmann]

Originally Posted by FHMbabe

Look at that writing!!! (0_0)

I've been told my writing is very heterosexual.