Trapezoidal Rule for Approximate Value of Definite Integral | Java program to implement Trapezoidal rule ; A sample function whose definite integral 's approximate value   is computed using Trapezoidal  rule ; Declaring the function f ( x ) = 1 / ( 1 + x * x ) ; Function to evaluate the value of integral ; Grid spacing ; Computing sum of first and last terms in above formula ; Adding middle terms in above formula ; h / 2 indicates ( b - a ) / 2 n . Multiplying h / 2 with s . ; Driver code ; Range of definite integral ; Number of grids . Higher value means more accuracy
class GFG { static float y ( float x ) { return 1 / ( 1 + x * x ) ; } static float trapezoidal ( float a , float b , float n ) { float h = ( b - a ) / n ; float s = y ( a ) + y ( b ) ; for ( int i = 1 ; i < n ; i ++ ) s += 2 * y ( a + i * h ) ; return ( h / 2 ) * s ; } public static void main ( String [ ] args ) { float x0 = 0 ; float xn = 1 ; int n = 6 ; System . out . println ( " Value ▁ of ▁ integral ▁ is ▁ " + Math . round ( trapezoidal ( x0 , xn , n ) * 10000.0 ) / 10000.0 ) ; } }