function sigfig,infig,nfigs

;	SIGFIG is a function which returns an input value (INFIG) as
;	a string rounded to the appropriate number of significant
;	figures (NFIGS), as taught by Bonnie Kelly, my high school 
; 	physics teacher.  


num=strtrim(string(infig),2)

n=intarr(10)
n(0)=strpos(num,'0')
n(1)=strpos(num,'1')
n(2)=strpos(num,'2')
n(3)=strpos(num,'3')
n(4)=strpos(num,'4')
n(5)=strpos(num,'5')
n(6)=strpos(num,'6')
n(7)=strpos(num,'7')
n(8)=strpos(num,'8')
n(9)=strpos(num,'9')
dec=strpos(num,'.')
epos=strpos(num,'e')
neg=strpos(num,'-')
errstr='Error: More Significant Figures than Input Digits'
length=strlen(num)-1.*(neg eq 0)

if length le nfigs then begin
	if dec ne -1 then begin
		print,errstr
		return,num
	endif
	if length lt nfigs then begin
		print,errstr
		return,strtrim(string(num,'.'),2)
	endif
endif

if epos ne -1 then begin
rnd1=strmid(num,0,nfigs+1)
rnd2=strmid(num,epos,6)
rnd=string(rnd1,rnd2)
return,rnd
endif
zerostring='00000000000'

if total(n(1:9)) eq -9 then begin
if dec eq -1 then return,'0'
rnd1='0.'
rnd2=strmid(zerostring,0,nfigs-1)
return,string(rnd1,rnd2)
endif

if n(0) eq 0 or ((neg eq 0) and (n(0) eq 1)) then begin
	n(where(n eq -1))=1000 
	firstval=min(n(1:9),subs)
	value=float(round(infig*10.^(firstval+nfigs-2)))*$
	(0.1^(firstval+nfigs-2))
	num=strtrim(string(value),2)
	rnd=strmid(num,0,firstval+nfigs)
endif else begin
	if dec eq -1 then begin
		dec=strlen(num)-1.*(neg eq 0) 
		nfig1=dec
	endif
	if dec le nfigs then nfig1=nfigs+1 else nfig1=dec
	
	n(where(n eq -1))=1000 
	firstval=min(n(1:9),subs)
	if neg eq 0 then begin
		nfig1=nfig1+1
		firstval=firstval-1
	endif
	exp=dec-(firstval+nfigs)
	value=float(round(infig*0.1^(exp)))*(10.^(exp))
	num=strtrim(string(value),2)
	return,strmid(num,0,nfig1)
endelse

return,rnd
end