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DiscountAmount

Function DiscountAmount( aValue, aDiscPC : Extended) : Extended

Example​

procedure ScriptEvent(var Value: Variant);
begin
  Value := DiscountAmount(250, 12.5); // 31.25
end;

Usage​

DiscountAmount calculates the unrounded discount amount for a value and percentage.

Parameters

NameTypeDescription
aValueExtendedBase value from which to calculate the discount.
aDiscPCExtendedDiscount rate expressed as a percentage; for example, 12.5 means 12.5%.

Returns

An Extended result equal to aValue * (aDiscPC / 100). The result is not rounded.

Behaviour

The function is pure: its result depends only on its two arguments. A rate of zero returns zero. A rate of 100 returns the supplied value.

Errors

The function has no explicit validation or exception handling. Floating-point or arithmetic failures raised by the runtime propagate to the script.

Usage notes

Use Discounted when the required result is the value after subtracting this amount. Apply an explicit output rounding rule when the result represents money.

Additional Technical Info​

DiscountAmount returns the discount component represented by a percentage of a supplied value. It is useful when the discount must be recorded separately from the resulting net value.

Implementation

Velox registers the function directly with the script runtime. The terminal Velox implementation divides the percentage by 100, multiplies it by aValue, and returns the arithmetic result without another wrapper or conversion.

Edge cases and quirks

  • The rate is a percentage, not a fractional multiplier. Passing 0.1 means 0.1%, not 10%.
  • Negative rates return a negative discount amount. Rates above 100% return an amount greater than the base value.
  • A negative base value reverses the sign expected from a positive base. The function does not impose accounting sign conventions.
  • The calculation uses binary floating-point Extended arithmetic and does not apply currency, banker's or commercial rounding. Delphi's Extended representation is platform dependent.

Performance and concurrency

The calculation is constant time, performs no allocation and accesses no shared Velox state. It is re-entrant subject to the host thread's floating-point environment.

Related entries

  • Discounted — returns the base value after the percentage discount.

External references

Created 2026-07-15