Perform Mathematical Calculations In Rules
It is possible to perform a variety of mathematical calculations using non-Boolean number and currency attributes. These operations include:
- standard arithmetic calculations (for example, addition, subtraction, multiplication, division)
- mathematical expressions (for example, square root, round, truncation, remainder)
- trigonometric calculations (for example, sine, cosine, tangent)
Numerical functions are used to perform these calculations. For the full list of supported functions, see Numerical functions.
The Loan Advisor example policy model that is installed with Policy Modeling contains many rules using arithmetic calculations. For example:
the payment interest amount = the payment balance * the monthly rate
the loan amount = the purchase price - the down payment
the loan duration in years = the loan duration / 12
Where multiple mathematical operations are included in a single rule, the standard mathematical preference is applied to operators in the absence of parentheses (that is, division, multiplication, addition, subtraction). In other words, these two rules are equivalent:
the loan to value ratio = the loan amount / the purchase price * 100
the loan to value ratio = (the loan amount / the purchase price) * 100
Tip: Using parentheses can make the calculation easier to read.
For more complex calculations, separating your rule into several steps can be beneficial. For example, while you could write:
the total payable = Maximum((the order total - Trunc((the order total * the discount percentage), 2) - the coupon amount),0)
breaking this down into four separate rules makes the calculations easier to understand and easier to test:
the total payable = Maximum(the total order amount including discounts and coupons, 0)
the total order amount including discounts and coupons = the order total - the order discount in whole dollars - the coupon amount
the order discount in whole dollars = Trunc(the order discount, 2)
the order discount = the order total * the discount percentage
Note: Be sure to use the exact syntax for the numerical functions as specified in the Function Reference, including spacing and parentheses. It is particularly important to include spaces either side of an mathematical operator. This is because if there is a letter or number on both sides of the operator, then the operator will be considered as part of the attribute text and will not function as an operator.
Examples of rules performing mathematical calculations, with inputs and outputs, are given in the table below.
Table 1. Examples of the use of the numerical functions
| Addition |
the household's total gross monthly income = the household's gross monthly earned income + the household's gross monthly unearned income
|
the household's gross monthly earned income: 1000
the household's gross monthly unearned income: 500
|
the household's total gross monthly income = 1500 |
| Subtraction |
the household's adjusted monthly income = the household's total gross monthly income - the household's monthly deductions
|
the household's total gross monthly income: 5000
the household's monthly deductions: 750
|
the household's adjusted monthly income = 4250 |
| Multiplication |
the default down payment amount = the purchase price * 0.2
|
the purchase price: 15000
|
the default down payment amount = 3000 |
| Division |
the weekly loan repayment amount = the loan amount / 1000
|
the loan amount: 90000
|
the weekly loan repayment amount = 90 |
| Number |
the number = Number(the number text)
|
the number text: 15 |
the number = 15 |
| Maximum |
the repayment amount = Maximum(50, the payment balance * 0.1)
|
the payment balance: 600
|
the repayment amount = 60 |
| Minimum |
the work-related child care costs = the lesser of the estimated annual child care expenses and the calculated amount of work-related child care costs
|
the estimated annual child care expenses: 8000
the calculated amount of work-related child care costs: 7500
|
the work-related child care costs = 7500 |
| Remainder (modulo) |
the remaining number = Remainder(the first number, the second number)
|
the first number: 10
the second number: 3
|
the remaining number = 1 |
| Exponentiation (xy) |
the result = Xy(the value,3)
|
the value: 5 |
the result = 125 |
| Mathematical Constant (ex) |
the result = Ex(the value)
|
the value: 0.3527 |
the result = 1.42290420813407 |
| Absolute value |
the result = Abs(the value)
|
the value: -80 |
the result = 80 |
| Natural Logarithm |
the result = Ln(the value)
|
the value: 0.3527 |
the result = -1.04213744174013 |
| Logarithm Base |
the result = Log(the value)
|
the value: 0.3527 |
the result = -0.45259454033251 |
| Square Root |
the result = Sqrt(the value)
|
the value: 64 |
the result = 8 |
| Round |
the result = Round(the value,3)
|
the value: 2.45678
|
the result = 2.457 |
| Truncation |
the result = Trunc(the value,1)
|
the value: 64.4657
|
the result = 64.4 |
| Sine |
the result = Sin(the value)
|
the value: 0.3527 |
the result = 0.345432860836779 |
| Cosine |
the result = Cos(the value)
|
the value: 0.3527 |
the result = 0.938443465880667 |
| Tangent |
the result = Tan(the value)
|
the value: 0.3527 |
the result = 0.368091284553421 |
| Inverse Sine |
the result = Asin(the value)
|
the value: 0.3527 |
the result = 0.360454968099581 |
| Inverse Cosine |
the result = Acos(the value)
|
the value: 0.3527 |
the result = 1.21034135869532 |
| Inverse Tangent |
the result = Atan(the value)
|
the value: 0.3527 |
the result = 0.339078136684554 |