use Math::BigFloat;

$f = Math::BigFloat->new($string);

# NSTR is a number string; SCALE is an integer value.
# In all following cases $f remains unchanged.
# All methods except fcmp() return a number string.
$f->fadd(NSTR);          # return sum of NSTR and $f
$f->fsub(NSTR);          # return $f minus NSTR
$f->fmul(NSTR);          # return $f multiplied by NSTR
$f->fdiv(NSTR[,SCALE]);  # return $f divided by NSTR to SCALE places
$f->fneg();              # return negative of $f
$f->fabs();              # return absolute value of $f
$f->fcmp(NSTR);          # compare $f to NSTR; see below for return value
$f->fround(SCALE);       # return rounded value of $f to SCALE digits
$f->ffround(SCALE);      # return rounded value of $f at SCALEth place
$f->fnorm();             # return normalization of $f
$f->fsqrt([SCALE]);      # return sqrt of $f to SCALE places
*****
$float = new Math::BigFloat "2.123123123123123123123123123123123";
*****
$f = Math::BigFloat->new("-20.0    0732");
$g = $f->fmul("-20.00732");
*****
max($div_scale, length(dividend)+length(divisor))
*****
$f = Math::BigFloat->new("20.00732");
$g = Math::BigFloat->new("1.7");
*****
$h = -20.00732 * 1.7;   # 34.012444 (ordinary math--$h is not an object)
$h = $f * $g;           # "34.012444" ($h is now a BigFloat object)
$h = $f * 1.7;          # "34.012444" ($h is now a BigFloat object)
$h = -20.00732 * $g;    # "34.012444" ($h is now a BigFloat object)
$h = $f->fmul($g);      # "+34012444E-6" ($h is now a BigFloat object)
$h = $f->fmul(1.7);     # "+34012444E-6" ($h is now a BigFloat object)