DOLLARFR

What it does

DOLLARFR(decimal_dollar, fraction)

DOLLARFR(decimal_dollar,fraction) converts an ordinary decimal amount to Excel’s fractional-quote numeric encoding. The digits after the decimal point encode a numerator over the supplied denominator; they are not an ordinary decimal fraction of the amount.

Try it

=DOLLARFR(12.375,32) returns about 12.12. The fraction 0.375 is twelve thirty-seconds, so the quote is twelve and 12/32. Reading 12.12 as an ordinary decimal amount would give a different value.

Quirks

The denominator is truncated. A negative denominator gives #NUM!; a denominator that truncates to zero gives #DIV/0!. The output is a number, not text containing a slash. Numerator digit width depends on the denominator’s decimal scale, and negative amounts need a consistent toward-zero integer part.

A power-of-ten denominator uses that power itself as the decimal scale, rather than one more digit position. The current helper therefore has an identity transform at denominators one and ten. It does not round the encoded numerator to an integer; arbitrary decimal inputs can encode fractional numerators.

How to implement

Split the admitted decimal amount into its toward-zero integer part and signed fractional part. For denominator f choose the kernel’s decimal scale 10^ceil(log10(f)); multiply the fractional part by f, divide by that scale and add the integer part. For f=32 the scale is 100, so 12+(0.375*32)/100=12.12. The current helper constructs the scale by multiplying by ten until it is at least the denominator, rather than taking a floating-point logarithm; use its retained code for those boundaries rather than assuming all algebraic orderings agree.

Rust code

29 dollarfr_fn "DOLLARFR" (2, 2) [V "decimal_dollar", V "fraction"] |s, a, sv| {
    if a.iter().any(CalcValue::is_missing) {
        return fail(W::NA);
    }
    out(s, dollar::dollarfr_kernel(dollar_num(s, a, 0)?, dollar_num(s, a, 1)?))
}

pub fn dollarfr_kernel(number: f64, fraction: f64) -> Result<f64, WorksheetErrorCode> {
    let denominator = normalized_fraction_denominator(fraction)?;
    let scale = decimal_scale(denominator);
    let whole = number.trunc();
    let fractional = number - whole;
    Ok(whole + fractional * denominator / scale)
}

No implementation has been published with a Handbook test suite for this function.

Version differences

The recorded environments below distinguish a reading from a same-input comparison. Counts describe captured inputs in each environment; overlapping captures and comparisons are not totals of unique worksheet calls.

The record contains no same-input comparison between these environments. Reading different inputs on different builds does not establish either a version change or cross-build agreement.

Recorded environments and comparison details.

Alternatives

DOLLARDE converts the quote back to an ordinary amount; TEXT can display a conventional written fraction when no numeric quote encoding is needed.

Named variants

No named variants are recorded yet.