subroutine iask(ival,str)
c      designed by c.e. mcilwain, 12/15/77 to 6/17/78
      byte str(1),ichar(40)
      do 5 i=1,80
      if(str(i).eq.0) go to 90
 5      continue
      i=80
 90      it=imax0(50-i,11)
 8      type 10,(str(j),j=1,i),ival
 10      format('$ cr if ok  ',t<it>,<i>a1,i8,' ? ')
       accept 112,nchar,(ichar(ii),ii=1,nchar)
 112      format(q,40a1)
d      type *,ichar,nchar
      if(nchar.eq.0) go to 115
      kb=0                        !non-blank flag
      do 30,ii=1,nchar
      if(ichar(ii).eq.32) go to 30      !blanks are  ok
      if(kb.eq.0 .and. (ichar(ii).eq.43. or. ichar(ii).eq.45))
     1   go to 20            !accept a leading + or -
      if(ichar(ii).eq.46) go to 40      !stop before a decimal point
      if(ichar(ii).lt.48 .or. ichar(ii).gt.57) go to 8
 20      kb=1                        !a non-blank character has been found
 30      continue
       go to 50
 40      nchar=ii-1
      if(nchar.eq.0) go to 8            !a miss-type? try again
 
 50      decode(nchar,114,ichar,err=90)ival
      it=imax0(it+i-13,37)
      type 111,ival
 111      format(t<it>,'  new value=',i8)
 114      format(i20)
 115      continue
      return
      end