made functions static to files

*BUG* in CPP lint github action

computer_oriented_statistical_methods/bisection_method.cpp

@@ -0,0 +1,40 @@
+#include <cmath>
+#include <iostream>
+
+static float eq(float i) {
+    return (std::pow(i, 3) - (4 * i) - 9);  // original equation
+}
+
+int main() {
+    float a, b, x, z;
+
+    for (int i = 0; i < 100; i++) {
+        z = eq(i);
+        if (z >= 0) {
+            b = i;
+            a = --i;
+            break;
+        }
+    }
+
+    std::cout << "\nFirst initial: " << a;
+    std::cout << "\nSecond initial: " << b;
+    for (int i = 0; i < 100; i++) {
+        x = (a + b) / 2;
+        z = eq(x);
+        std::cout << "\n\nz: " << z << "\t[" << a << " , " << b
+                  << " | Bisect: " << x << "]";
+
+        if (z < 0) {
+            a = x;
+        } else {
+            b = x;
+        }
+
+        if (z > 0 && z < 0.0009)  // stoping criteria
+            break;
+    }
+
+    std::cout << "\n\nRoot: " << x;
+    return 0;
+}