Re: simple plot

[Arindam Chakraborty <arch@xxxxxxxxxxxxxx>]

hi Wendy,
	you can do it in the following way:

 let xv = temp[k=2]; ! define variable which will be along x-axis
 let yv = s[k=2]; ! define variable which will be along y-axis

! plot the data
 plot/vs/sym=1 xv, yv

! now make the linear fit using least square method
! basically calculate ave and amp of the equation: y = amp*x + ave

 let xy = xv*yv
 let xx = xv*xv

 let p = xv[x=@sum,y=@sum]
 let q = yv[x=@sum,y=@sum]
 let r = xy[x=@sum,y=@sum]
 let s = xx[x=@sum,y=@sum]

 let n = xy[x=@ngd,y=@ngd]
 list n

 let amp =  (n*r - p*q)/(n*s - p*p)
 let ave = (q - amp*p)/n

 list amp, ave


Hope this helps,

----------------------------
 ARINDAM CHAKRABORTY
 Department of Meteorology
 Florida State University
 Tallahassee, FL-32306, USA
 Tel: +001-850-6443524 (Off)
      +001-850-5758550 (Res)
 Fax: +001-850-6449642
 email: arch@io.met.fsu.edu
        arindam@met.fsu.edu
____________________________

On Fri, 5 Nov 2004, Wendy Wang wrote:

> Hi ferret_users,
> 
> I have a dataset like:
> 
>   name     title                                  I         J         K 
>      L
>   S        Salinity                         1:161     1:91      1:21      1:636
>   TEMP     Temperature              1:161     1:91      1:21      1:636
> 
> I want to make one scatter plot using k=2 data:
> X axis is temp, Y axis is S. Then do the linear fit.
> 
> Does someone know how? It may be simple,
> but I cannot figure it out.
> 
> Thanks in advance.
> Wendy Wang 
>