# F# Math Operators: abs, floor and ceil

Perform computations on numbers with math operators. Call pown, abs, floor and ceil.**Math.** N is -10. Now it is 10. An absolute value is always positive. We can compute this with some logic. But abs is built-in—it is easier to call.

**With special operators,** we call built-in mathematical methods. For example, with "pown" we compute an exponent of an integer. This makes programs clearer to read.

**Exponents.** Let us begin with some exponentiation. Please note that we can call methods from System.Math also, but F# provides some shortcuts.

**Pown:** We first use pown to take the power of a number (an int). We square the value 4 to get 16.

**Exponents:** We use two starts to apply a power to a double. We must use 2.0 instead of 2 to square here.

**F# program that uses pown, exponents**
*// Use pown to implement integer exponents.
*let number = *4*
let squared = __pown__ number *2*
printfn "%A" squared*
// Use two stars to implement double-type exponents.
*let numberDouble = *4.0*
let squaredDouble = numberDouble ** *2.0*
printfn "%A" squaredDouble
**Output**
16
16.0

**Abs.** The absolute value of a number is positive. Numbers that are already positive are not changed. Abs is useful when computing indexes (like with hash codes).

**F# program that uses abs**
*// The absolute value of -10 is 10.
*let result1 = __abs__ *-10*
printfn "%A" result1*
// For positive numbers, nothing is changed.
*let result2 = __abs__ *1*
printfn "%A" result2
**Output**
10
1

**Floor, ceil.** We have operators that access many common math methods. For example floor and ceil access the Math.Floor and Math.Ceiling methods.

**F# program that uses floor and ceil**
*// Take the floor of a number with the operator.
*let result1 = __floor__ 2.9
printfn "%A" result1*
// Take ceiling of a number.
*let result2 = __ceil__ 1.1
printfn "%A" result2
**Output**
2.0
2.0

**Max, min.** We pass two Int arguments to these functions. They return the bigger (for max) or the smaller number (for min). These are built into the F# language.

**F# program that uses max, min**
let numberSmaller = *10*
let numberBigger = *20**
// Get the max of the two numbers.
*let bigger = __max__ numberSmaller numberBigger
printfn "%A" bigger*
// Get the min.
*let smaller = __min__ numberSmaller numberBigger
printfn "%A" smaller
**Output**
20
10

**Odd, even.** A number can be odd or even—this is the parity of the number. In F# we use Seq.where to filter based on the parity of numbers. We even generate odd and even sequences.

Odd, Even**A summary.** F# programs often extensively use numbers. We find these mathematical operators make programs easier to understand to write. When compatible, they should be preferred.

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