Release List Reviews Shop Join News DVD Giveaways Video Games Advertise
DVD Reviews | Theatrical Reviews | Price Search Buy Stuff Here
DVD Talk
DVD Reviews DVD Talk Headlines HD Reviews


Add to My Yahoo! - RSS 2.0 - RSS 2.0 - DVD Talk Podcast RSS -


Go Back   DVD Talk Forum > General Discussions > Tech Talk

Tech Talk Discuss PC Hardware, Software, Internet and Other Technology

Reply
 
Thread Tools
Old 02-18-03, 09:41 PM   #1
DVD Talk Special Edition
 
Join Date: Jan 2001
Location: Raleigh, NC
Posts: 1,665
Quick Question about Excel Charts

I have a function ( y = f(x) ) that I want to graph in Excel in an xy scatter plot. I usually just make a column of x values and then a column for the y values as a function of the first column, then make the plot based on this set of about 20 points. Is there any way to make a plot straight from the equation, like you would in a graphing calculator?

I hope I'm making myself clear, but if not, let me know and I'll try to elaborate. The function isn't of the type that can have a trend line or polynomial fit, so I can't just do the regression and use that as the function.

I guess I might as well put the equation I'm using:

y = a*x/(1+(a-1)*x) where 'a' is a known constant
  Reply With Quote
Old 02-18-03, 10:51 PM   #2
DVD Talk Hall of Fame
 
Join Date: Oct 1999
Location: not CT
Posts: 9,483
In short, no ... not to my knowledge. Your only hope would be to generate a crapload of points and the try to get excel to apply the right trendline to it so it would return the original equation. I don't think it can create something in that form, though.
  Reply With Quote
Old 02-18-03, 10:53 PM   #3
DVD Talk Special Edition
 
Join Date: Jan 2001
Location: Raleigh, NC
Posts: 1,665
That's what I figured, but thanks anyway. I was just curious
  Reply With Quote
Old 02-18-03, 10:58 PM   #4
DVD Talk Hall of Fame
 
Join Date: Oct 1999
Location: not CT
Posts: 9,483
Quote:
Originally posted by sdcrym
That's what I figured, but thanks anyway. I was just curious
Yeah, I guess I didn't really bother to read past your first sentence or I would have known you knew all that and I could have just said 'no' ... oops.
  Reply With Quote
Old 02-19-03, 12:26 AM   #5
DVD Talk Ultimate Edition
 
Join Date: Jan 2001
Location: Gator Nation
Posts: 4,571
Actually I really need help too and was about to start my own thread. I need to make a graph using specific plot points (x,y) and need to find the linear equation of the best fit line y=mx+b how do I do that?

Its for chemistry. I'm plotting a standard curve for a Bradford and BCA assay in order to find the concentration for an unknown sample. If you were curious.
  Reply With Quote
Old 02-19-03, 01:44 AM   #6
DVD Talk Special Edition
 
Join Date: Jan 2001
Location: Raleigh, NC
Posts: 1,665
Well, my response to you depends on how much you know about Excel already. In short, highlight the x and y columns in a spreadsheet, click the make chart button, select xy scatter. Make sure the next page has the x's and y's in the right place. I'm leaving out a lot of details, but you should be able to figure it out. After the scatter plot is displayed, right click on a data point and select add trendline. Make sure linear is selected, then move over to the options tab and check the display equation box.

Sorry for the incoherence... I just finished up my homework and now I'm off to bed
  Reply With Quote
Old 02-19-03, 08:29 PM   #7
DVD Talk Ultimate Edition
 
Join Date: Jan 2001
Location: Gator Nation
Posts: 4,571
Thank you very much! your help is much appreciated. I could figure it out.
  Reply With Quote
Reply


Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -5. The time now is 09:30 AM.


Copyright 2011 DVDTalk.com All Rights Reserved. Privacy Policy and Terms of Use.

Content Relevant URLs by vBSEO 3.2.0