update readme with sqrt explication

src/solver.c

@@ -71,8 +71,6 @@ static int find_gcd(double numerator, double denominator)
 /*
 typedef struct
 {
-    double a;                 // a in "ax + b"
-    double b;                 // b in "ax + b"
     int solution_gcd;         // gcd(b, a)
     int solution_numerator;   // -b / gcd
     int solution_denominator; //  a / gcd
@@ -82,19 +80,20 @@ typedef struct
 /*
 typedef struct
 {
-    double a;                    // a in "ax² + bx + c"
-    double b;                    // b in "ax² + bx + c"
-    double c;                    // c in "ax² + bx + c"
     e_delta_sign delta_sign;     // DELTA_PLUS or DELTA_MINUS or DELTA_ZERO
     double delta_absolute;       // |Δ| == |b² - 4ac|
+    double delta_sqrt;           // √|Δ|
+
     int first_term_gcd;          // gcd(b, 2a)
     int first_term_numerator;    // -b / gcd
     int first_term_denominator;  // 2a / gcd
     double first_term;           // double (-b / 2a)
+
     int second_term_gcd;         // gcd(√|Δ|, 2a)
     int second_term_numerator;   // √|Δ| / gcd
     int second_term_denominator; // 2a / gcd
     double second_term;          // double (√|Δ| / 2a)
+
     double solution1;            // first_term + second_term
     double solution2;            // first_term - second_term (not if DELTA_ZERO)
 } s_solution_degree_2;
@@ -107,11 +106,16 @@ static void solve_degree_2(s_solution_degree_2 *solution, double a, double b, do
     delta = b * b - 4 * a * c;
     solution->delta_sign = ft_fsign(delta);
     solution->delta_absolute = ft_fabs(delta);
+    solution->delta_sqrt = ft_sqrt(solution->delta_absolute);
+
+    // first term
     solution->first_term_gcd = find_gcd(b, 2 * a);
     solution->first_term_numerator = -b / solution->first_term_gcd;
     solution->first_term_denominator = 2 * a / solution->first_term_gcd;
     solution->first_term = -b / (2 * a);
-    // solution->second_term_gcd = ;
+
+    // second term
+    // solution->second_term_gcd = find_gcd(b, 2 * a);
     // solution->second_term_numerator = ;
     // solution->second_term_denominator = ;
     // solution->second_term = ;