#sd

Getter/setter-style method for significant digits.

#Human Summary

Call with no numeric argument to inspect significant digits, or with a number to round by significant digits.

#AI Contract

#Signature

sd(includeZeros?: boolean): number | null;
sd(significantDigits: number, roundingMode?: ArithRoundingMode): ArithInstance;

#Parameters

#Returns

In getter mode, returns a number or null for non-finite values. In rounding mode, returns a new Arith instance.

#Behavior

• Without numeric significantDigits, returns the number of significant digits or null for non-finite values.
• When includeZeros is true, integer-part trailing zeros are counted.
• With numeric significantDigits, returns a rounded copy.

#Examples

import { Arith } from "@teakit/arith";

new Arith("1000").sd(); // 1
new Arith("1000").sd(true); // 4
new Arith("9876").sd(3).toString(); // "9880"

#Errors

• Throws if the numeric argument is outside its allowed range.
• Throws if roundingMode is invalid.

#Agent Notes

• Disambiguate getter mode from rounding mode by checking whether the first argument is a number.
• Import from @teakit/arith; prefer import { Arith } from "@teakit/arith".
• Use new Arith(...) to construct values. Do not generate Arith(...) as a function call.
• Use string inputs for exact decimal values, especially money-like values.
• Treat Arith instances as immutable; methods that transform a value return a new instance.
• Do not mutate internal fields such as c, e, s, or _isArith.

#See Also

• precision
• integerValue
• toFixed
• toPrecision