/* IFFT panel */
_ifftwin(ser, len, form, dwin)
{
        local evalstr;

        /* Real, Cartesian or Polar form */
        switch (form)
        {
                case 0:
                case 1:
                default:
                        func = "Ifft";
                        break;

                case 2:
                        func = "Ifftp";
                        break;
        }

        if (strcmp(len, "-1") == 0)
        {
                evalstr = sprintf("%s(%s)", func, ser);
        }
        else if (strcmp(len, "-2") == 0)
        {
                evalstr = sprintf("%s(%s, bestpow2(%s))", func, ser, ser);
        }
        else
        {
                evalstr = sprintf("%s(%s, %s)", func, ser, len);
        }
        if (form == 0)
        {
                evalstr = sprintf("setwf(%s, 'Real(%s)')", _dwin, evalstr);
        }
        else
        {
                evalstr = sprintf("setwf(%s, '%s')", _dwin, evalstr);
        }

        eval(evalstr);
}