function strdigits,number,digits

number=double(number)
digits=round(digits)
if digits gt 0 then begin
  number=double(round(number*(long64(10)^digits),/l64))/double((long64(10)^digits))
  temp=strsplit(strcompress(string(number),/remove_all),'.',/extract)
  knowndigits=strlen(temp[1])
  if digits le knowndigits then output=temp[0]+'.'+strmid(temp[1],0,digits) else output=temp[0]+'.'+temp[1]+strmid('0000000000000000000',0,digits-knowndigits)
endif else begin
  number=long64(round(number/long64(10)^(-digits))*long64(10)^(-digits))
  output=strcompress(string(number),/remove_all)
endelse

return,output

end