F# is great for creating quick mathematical calculations. One good use of F# is to compute roots from the quadratic equation. To get both roots of the quadratic from entered coefficients, you can create a tuple from the quadratic equation:
let quad (a,b,c) = (((-b + Math.Sqrt((b*b) - (4.0*a*c)))/(2.0*a)), ((-b + Math.Sqrt((b*b) - (4.0*a*c)))/(2.0*a)));;
val quad : float * float * float -> float * float
The result of the equation ax2 + bx + c for (a =1 , b= 2, and c = 1) is shown below (in other words the roots for x2 + 2x + 1):
> quad (1.0,2.0,1.0);;
val it : float * float = (-1.0, -1.0)
A little less reduntant F# code could be created by breaking out the sqrt part of the equation and feeding the result back into the quadratic.
>
let q (a, b, c) = Math.Sqrt(b*b - 4.0*a*c)
let quad (a,b,c) = ((-b + q(a,b,c))/(2.0*a), (-b - q(a,b,c))/(2.0*a));;
val q : float * float * float -> float
val quad : float * float * float -> float * float
Note we get the same results:
> quad (1.0,2.0,1.0);;
val it : float * float = (-1.0, -1.0)
We can also try for other coefficients such as the equation x2 - 4x - 5 where (a=1, b=-4, and c=-5) :
> quad (1.0, -4.0, -5.0);;
val it : float * float = (5.0, -1.0)
After playing in the interactive window for a bit, I decided to create a real F# project in visual Studio. I added a new test.fs file to my project
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Then I added the following code to test.fs:
open
System; // open the .NET System library
let q (a, b, c) = Math.Sqrt(b*b - 4.0*a*c) // create the set of quadratic equations for calculating the root
let quad (a,b,c) = ((-b + q(a,b,c))/(2.0*a), (-b - q(a,b,c))/(2.0*a));;
let v = (quad(1.0, 2.0, 1.0));; // compute the root of x2 + 2x + 1
print_string "The root is "; // print out the root using the F# print functions
print_any v;
Console.ReadLine() // prevent the console from closing until enter is hit
The results of running the program are shown below:
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More on the printing functions in my next blog....