comp.lang.idl-pvwave archive: archive

Home » Public Forums » archive » Help!!!!

Show: Today's Messages :: Show Polls :: Message Navigator
E-mail to friend

Re: Help!!!! [message #90810 is a reply to message #90809]

Sat, 18 April 2015 12:26

rryan%stsci.edu
Messages: 16
Registered: October 2014

Junior Member

On Saturday, April 18, 2015 at 1:25:30 PM UTC-4, alep...@gmail.com wrote:
> How to linear and robust adjustment ?
> LINFIT : y = A + Bx
> LINFIT result = (X, Y = MEASURE_ERRORS measure_errors )
> PRINT , result
>
> What data put in X , Y ?

It sounds like your professor is trying to get you to infer the Hubble constant from a bunch of data. He or she must have given you some data. Those data are x and y. At a fundamental level, it matters which is which, and you should try to understand that. Typically you have a "dependent" and "independent" variable. You need to realize which is which, of course I know, but I can't just tell you. Start by thinking what physically does Hubble constant represent? What are its units? km/s per Mpc. Now, what are the units of a slope of a line? Which variable should be x and should be y, now?

Once you get that sorted out, the IDL code is simple...

http://www.exelisvis.com/docs/LINFIT.html

result = linfit (x, y, measure_errors=dy)

where dy are the errors on y.

Report message to a moderator

[Message index]

		Help!!!! By: alepliee on Sat, 18 April 2015 07:15
		Re: Help!!!! By: rryan%stsci.edu on Sat, 18 April 2015 09:21
		Re: Help!!!! By: alepliee on Sat, 18 April 2015 10:25
		Re: Help!!!! By: rryan%stsci.edu on Sat, 18 April 2015 12:26
		Re: Help!!!! By: alepliee on Sat, 18 April 2015 20:29

Previous Topic:	"Subtitle=" in Function graphics
Next Topic:	mrd_struct failure for string values inside the VM

-=] Back to Top [=-

[ Syndicate this forum (XML) ] [

] [

]

Current Time: Wed Oct 08 15:47:29 PDT 2025

Total time taken to generate the page: 0.00425 seconds