SEMF physical C ++ code
Need help solving one minor issue with this program. I created a SEMF in physics for C ++ to calculate the formula everything is fine, but my BE is a formula with a5 in it.
He says about the error: The identifier "a5" is undefined, and I know what it means, but how can I get the a5 that needs to be taken from the select statement, if I entered even even or even odd or odd values for the AZ values.
#include <iostream>
#include <cstdlib>
#include <math.h>
using namespace std;
int main()
{
int A, Z;
// Main body of Semi-Empirical Mass Formula
cout <<"Enter the mass number A: ";
cin >> A;
cout <<"\n";
cout <<"Enter the atomic number Z: ";
cin >> Z;
cout <<"\n";
// Constants from formula, units in MeV(millions of electron volts)
double a1 = 15.67;
double a2 = 17.23;
double a3 = 0.75;
double a4 = 93.2;
if(Z % 2 == 0 && (A - Z) % 2 == 0)
double a5 = 12.0;
else if(Z % 2 != 0 && (A - Z) % 2 != 0)
double a5 = -12.0;
else
double a5 = 0;
// Formula for to compute the binding energy
double B =a1 * A - a2 * pow( A, 2/3) - a3 * (pow(Z, 2) / pow(A, 1/3)) - a4 * (pow(A - 2 * Z, 2) / A) + (a5 / pow(A, 1/2));
// Formula for to compute the binding energy per nucleon
double B_E = B / A;
return 0;
}
Put definition
double a5 = 0.0;
just below the definition of a4 and use it in each of your if cases.
a5 is undefined due to scope issue.
Since you are declaring a5 in the clauses of the if-else statement, the declaration is only scoped in the statement that is being declared.
To fix this problem, declare a5 in a location where it is scoped to later statements where you use a5:
double a1 = 15.67;
double a2 = 17.23;
double a3 = 0.75;
double a4 = 93.2;
double a5 = 0.0;
//^ declare a5 here, it will be in scope when used in subsequent statements past the else clause
if(Z % 2 == 0 && (A - Z) % 2 == 0)
a5 = 12.0;
else if(Z % 2 != 0 && (A - Z) % 2 != 0)
a5 = -12.0;
// Formula for to compute the binding energy
double B =a1 * A - a2 * pow( A, 2/3) - a3 * (pow(Z, 2) / pow(A, 1/3)) - a4 * (pow(A - 2 * Z, 2) / A) + (a5 / pow(A, 1/2));
You need to declare a5
outside of your if statements and then set it in if statements
double a5 = 0;
if(Z % 2 == 0 && (A - Z) % 2 == 0)
a5 = 12.0;
else if(Z % 2 != 0 && (A - Z) % 2 != 0)
a5 = -12.0;
As you are now, the variable a5
will only exist inside the if statement in which it is declared.
Move the ad a bit a5
:
double a5;
if(Z % 2 == 0 && (A - Z) % 2 == 0)
a5 = 12.0;
else if(Z % 2 != 0 && (A - Z) % 2 != 0)
a5 = -12.0;
else
a5 = 0;