# IRR ( cashFlowsList ; guessRate )

Calculate Internal Rate of Return of a value list of cash flows with an initial guessed rate-of-return, using the Newton-Raphson method.

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Function definition: (Copy & paste into FileMaker's Edit Custom Function window)

IRR ( cashFlowsList ; guessRate )

Created: 4-5-2013

Modified: 1-3-2014

Author: Lewis C. Lorenz

Calculate Internal Rate of Return of a value list of cash flows (cashFlowsList) using an initial guessed rate of return (guessRate). The parameter guessRate defaults to .0001 if initially blank.

This function uses the Newton-Raphson method for speed and calculates to a modifiable decimal precision - presently set at 1.0e-7. The C source code from which this custom function was derived is included in the comments.

Examples:

IRR ( "-500000¶200000¶300000¶200000" ; .1 ) = .1882462096837047

IRR ( List ( -2000 ; 600 ; 300 ; 500 ; 700 ; 400 ) ; .05 ) = .0793216878811758

IRR ( List ( -5000 ; 10000 ; 0 ; 10000 ; 10000 ) ; .1 ) = 1.4633789720926647

DISCLAIMER: Using this IRR function, several calculations were compared against the results obtained on other IRR calculators and the results matched. However, that does not guarantee a correct result in every operation of this custom function, so you assume this risk when you use it.

NOTICE: This is a recursive function. If you change the function name then also change it in the function code.

## Comments

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