simpsons 1/3rd rule implementation

Author: ashish-ratn

simpsons_method.c

@@ -0,0 +1,42 @@
+#include <math.h>
+#include <stdio.h>
+
+float f(float x)
+{
+    return 1.0 +
+           x * x * x;  // This is the expresion of the function to integrate?
+}
+
+int main()
+{
+    int i, n;
+    float a, b, h, x, s2, s3, sum, integral;
+
+    printf("enter the lower limit of the integration:");
+    scanf("%f", &a);
+    printf("enter the upper limit of the integration:");
+    scanf("%f", &b);
+    printf("enter the number of intervals:");
+    scanf("%d", &n);
+
+    h = (b - a) / n;
+    sum = f(a) + f(b);
+    s2 = s3 = 0.0;
+
+    for (i = 1; i < n; i += 3)
+    {
+        x = a + i * h;
+        s3 = s3 + f(x) + f(x + h);
+    }
+
+    for (i = 3; i < n; i += 3)
+    {
+        x = a + i * h;
+        s2 = s2 + f(x);
+    }
+
+    integral = (h / 3.0) * (sum + 2 * s2 + 4 * s3);
+    printf("\nValue of the integral = %9.4f\n", integral);
+
+    return 0;
+}