FUNCTION tilt,bestpic
;NAME:tilt
;
;PURPOSE:to find the angle of the slit with respect to the chip
;
;CALLING SEQUENCE:
;
;INPUTS:name of the "pic" - csmm pos -that has the most flux - pic(*,*,csmm)
;
;OPTIONAL KEYWORD:
;
;OUTPUTS: an array of three: slope, y-int and angle of tilt
;
;SIDE EFFECTS:??
;
;RESTRICTIONS:??
;
;EXAMPLES:
;
;MODIFICATION HISTORY:started on 1/3/03
;
;------------------------------------

PRINT, "Finding the tilt between the array and the slit"
;name=''
;READ, name, PROMPT='Enter file name:'

;cube=RDFITSCUBE(name)

;best=pic(*,*,smMax)
best=bestpic
;PRINT, 'Number of bins can be: 1,2,4,8,16, or 32'
PRINT, 'If there is not enough flux in a single pixel,'
PRINT, 'Then you can bin several together.'
PIX:
PRINT, 'Number of pixels per bin can be: 1,2,4,8, or 16'
READ, nbin2, PROMPT='How many pixels in each bin?'
If(nbin2 ne 1 and nbin2 ne 2 and nbin2 ne 4 and nbin2 ne 8 and  $
  nbin2 ne 16 and nbin2 ne 32) Then begin
PRINT, 'Number of bins must divide into 32. Try again.'
Goto, Pix
ENDIF
nbin=32/nbin2
maxcol=fltarr(nbin)
xs=fltarr(nbin)
xys=fltarr(nbin)
xsquare=fltarr(nbin)
k=0
again=''
iter=32/nbin

IF (nbin eq 32) then begin
bin=best
GOTO, maxbins
Endif


;bin the rows
bin=fltarr(32,nbin)
for i=0,nbin-1 do BEGIN 
   bin(*,i)=TOTAL(best(*,(i*iter):(i+1)*iter-1),2)
endfor

maxbins:
;fit the bined rows
for i=0,nbin-1 DO Begin

;start with fitting all cols
fit1=0
fit2=23
fitloop:
;Plot, bin(*,i), Title='Bin '+STRING(i),ytit='fluxes in DN/sec',$
;  xtit='col #',background=255, color=0, xticklen=1,xgridstyle=1,$
;   xticks=7

x=dindgen(fit2-fit1+1)
for j=0,(fit2-fit1) do x(j)=fit1+j
;SPLINE_P,x, bin(fit1:fit2,i), XR,YR

;fit spline with mpfitpeak
A=fltarr(4)
;quadfit=MPFITPEAK(xr,yr,A)
yfit=MPFITPEAK(x,bin(fit1:fit2,i),A)
PRINT, 'Coeff: ', A
Mcol=A(1)
maxcol(k)=mcol
xs(k)=i
PRINT, 'Max col: ',MAXCOL(k)

;get finer grid for gaussian check
x2=fltarr(n_elements(x)*4)
x2(0)=x(0)
x2(n_elements(x2)-1)=x(n_elements(x)-1)
xrange=x(n_elements(x)-1)-x(0)
for j=1,n_elements(x2)-2 do x2(j)=x2(0)+j*(xrange/n_elements(x2))
z=(x2-A(1))/A(2)
check=A(0)*EXP(-0.5*z^2)+A(3)
checkbig=MAX(check)
PLOT, x,bin(fit1:fit2,i),title='Fits to Bin'+STRING(i), ytit='Flux',$
   xtit='Col #', background=255, color=0,yrange=[0,checkbig]
;OPLOT,XR,YR,linestyle=2,color=100
OPLOT,X2, check, linestyle=3,color=40
Maxrow=MAX(bin(fit1:fit2,i),mr)

PRINT,'Do you want to use the max row? (r) It is row',mr+fit1
READ, again, PROMPT='Or, is this fit ok? (y/n):'
If (again eq 'r') THen maxcol(k)=mr+fit1
IF (again eq 'n') Then begin
;get which cols to fit:
oops:
READ, fit1,Prompt='Where should the fit start?'
READ, fit2,PROMPT='Where should the fit end?'
   if (fit2-fit1 le 3) then begin
   PLOT, x,bin(fit1:fit2,i),title='Fits to Bin'+STRING(i), ytit='Flux',$
   xtit='Col #', background=255, color=0,yrange=[0,checkbig]
   oplot,X2, check, linestyle=3,color=40
   print, 'There must be more than 3 columns to fit.'
   goto, oops
   endif
goto, fitloop
endif

k=k+1
endfor

IF (nbin eq 1) then begin
Print, 'Maximum column is at: ', maxcol(0)
m=0
b=maxcol(0)
goto, onebin
Endif

;fit line to maxcol
;PRINT,maxcol
;PRINT, 'Change values of maxcol if needed.'
;STOP
for h=0,nbin-1 do begin
 xys(h)=xs(h)*maxcol(h)
 xsquare(h)=xs(h)*xs(h)
endfor
ys=maxcol

delta=(nbin*TOTAL(xsquare)-(TOTAL(xs))^2)
;Slope
 m=(nbin*TOTAL(xys)-TOTAL(xs)*TOTAL(maxcol))/delta
;y intercept
 b=(TOTAL(xsquare)*TOTAL(maxcol) - TOTAL(xs)*TOTAL(xys))/delta

;UNCERTAINTIES
;sigma^2
sigma2=(TOTAL((ys-(m*xs+b))^2))/(k-2)
;y-intercept uncertainty squared
 intsigma2=(sigma2/delta)*TOTAL(xs^2)
;slope uncertainty squared
slopesigma2=k*sigma2/delta




PRINT, 'Slope= ',m,'  +/-', SQRT(slopesigma2)
PRINT, 'Y-Int= ',b,'  +/-',SQRT(intsigma2)
PRINT, 'Angle= ',ATAN(m)
PLOT, xs, (m*xs+b),xtit='bin #', ytit='col #'


Close, 15
OPENW,15, 'Tilt_details',/APPEND
PRINTF,15, ' '
PRINTF,15, 'Number of pixels/bin:',nbin2
PRINTF,15, 'Slope: ',m,'  +/-', SQRT(slopesigma2)
PRINTF,15, 'Y-Int= ',b,'  +/-',SQRT(intsigma2)
PRINTF,15, 'Angle= ',ATAN(m)

Close,15


onebin:
RETURN, [m,b,ATAN(m),SQRT(slopesigma2),SQRT(intsigma2)] 
END