GNU Free Documentation License, Version 1.2

- Examples
- User documentation
- Maintainer documentation
- Bugs, shortcomings and other ideas
- Main changes

These functions are to help visualize integer and rational numbers in
a more comprehensible format (as a decimal `string`

). The `SigFig`

argument is optional; its default value is 5.

`ToString(N)`

converts`N`

to a (decimal) string.`FloatStr(N, SigFig)`

convert the number`N`

into a string choosing between "decimal" format and "scientific" format. The default value for`SigFig`

is 5.`ScientificStr(N, SigFig)`

convert the number`N`

into a string of the form mantissa times power-of-ten, with`SigFig`

digits in the mantissa. Note that trailing zeroes are not removed from the mantissa.`DecimalStr(N, DecPlaces)`

convert the number`N`

into a decimal string with`DecPlaces`

digits after the decimal point. The default value for`DecPlaces`

is 3.

Note: for values with large numerator or denominator it is quicker to convert
the value to a `RingElem`

belonging to a `RingTwinFloat`

and then print
the result. This approach offers less control over the output, and no
guarantee of correct rounding.

The function `ScientificStr`

gives the clearest guarantees about the
format used, but also produces the least humanly readable result. It
uses `MantissaAndExponent10`

to do the conversion.

The function `FloatStr`

is supposed to be the best general choice.
It passes its args to `ScientificStr`

in two situations: if the
number is so large that padding would be needed before the decimal
point; if the number is so small that the `ScientificStr`

format
would be shorter (*i.e.* if the exponent is less than -8).

The function `DecimalStr`

is Anna's preferred choice. It uses
`ToString`

to convert to decimal.

These functions cannot be applied directly to a machine integer; to call
them you have to convert explicitly into a `BigInt`

(or `BigRat`

).

The switch-over in `FloatStr`

to scientific notation for "large"
numbers is not ideal; in C the "g" format chooses the shorter between
float and scientific formats. Is it worth the doing the same here?

Anna says an older version of `DecimalStr`

would suppress trailing zeroes
if the result is exact (*e.g.* `DecimalStr(5/4,9)`

would produce `1.25`

rather than `1.250000000`

. Is this a good idea?

These fns are too slow if `N`

is a very large integer (or if numerator
and/or denominator are very large). Converting to an `mpf_t`

and
printing that would be much faster (except in delicate rounding cases).

**2014**

- April (v0.99533): reorganized, renamed
`FloatStr`

to`ScientificStr`

, added new`FloatStr`

**2011** - February (v0.9943): first release