Module tvm 

Time-value-of-money equations without level payments: present value, future value, rate, and periods (simple and continuous compounding, fixed rate or rate schedules).

Error handling (v0.1+)

Public entry points return crate::FinanceResult. Invalid rates (e.g. less than −100% per period), non-finite amounts, and unsolvable sign combinations produce crate::FinanceError — they do not panic.

use finance_solution::{future_value, FinanceResult};

fn demo() -> FinanceResult<f64> {
    future_value(0.05, 10, -1_000.0, false)
}
debug_assert!(demo().is_ok());

Compounding

Pass Compounding::Periodic (or false via From) for discrete compounding, or Compounding::Continuous (or true) for continuous compounding.

Modules

future_value

Future value calculations. Given an initial investment amount, a number of periods such as periods, and fixed or varying interest rates, what is the value of the investment at the end?

periods

Number of periods calculations. Given a periodic rate, present value, and future value, find the number of periods needed to satisfy the equation.

present_value

Present value calculations. Given a final amount, a number of periods such as years, and fixed or varying interest rates, what is the current value?

rate

Periodic rate calculations. Given an initial investment amount, a final amount, and a number of periods what does the rate per period need to be?

Structs

TvmPeriod

The value of an investment at the end of a given period, part of a Time Value of Money calculation.

TvmScheduleSolution

A record of a Time Value of Money calculation where the rate may vary by period.

TvmSeries

TvmSolution

Enums

Compounding

How interest compounds in a TVM calculation.

TvmVariable

Enumeration used for the calculated_field field in TvmSolution and schedule solutions to track what was calculated: periodic rate, number of periods, present value, or future value.

Functions

future_value

Returns the value of an investment after it has grown or shrunk over time, using a fixed rate.

future_value_schedule

Calculates a future value based on rates that change for each period.

future_value_schedule_solution

Calculates a future value based on rates that change for each period, returning a struct with all of the inputs and results.

future_value_solution

Calculates the value of an investment after it has grown or shrunk over time and returns a struct with the inputs and the calculated value. This is used for keeping track of a collection of financial scenarios so that they can be examined later.

periods

Returns the number of periods given a periodic rate along with the present and future values, using simple compounding.

periods_solution

Calculates the number of periods given a periodic rate along with the present and future values using simple compounding; and builds a struct with the input values, an explanation of the formula, and the option to calculate the period-by-period values.

present_value

Returns the current value of a future amount using a fixed rate.

present_value_schedule

Calculates a present value based on rates that change for each period.

present_value_schedule_solution

Calculates a present value based on rates that change for each period and returns a struct with the inputs and the calculated value.

present_value_solution

Calculates the current value of a future amount using a fixed rate and returns a struct with the inputs and the calculated value. This is used for keeping track of a collection of financial scenarios so that they can be examined later.

rate

Returns the periodic rate of an investment given the number of periods along with the present and future values.

rate_solution

Returns the periodic rate of an investment given the number of periods along with the present and future values.