edge case in mortgage loan

1 files changed, 8 insertions, 2 deletions

diff --git a/mortgage_loan.c b/mortgage_loan.c
index a9ab28b..2751aff 100644
--- a/mortgage_loan.c
+++ b/mortgage_loan.c
@@ -13,12 +13,18 @@ contract *mort_init(int n, int d, double r, double P) {
 }
 
 double mort_update(contract *c) {
+	double tmp;
 	if (c->k > c->n)
 		return 0.0;
 
 	if (c->k == c->d) {
-		c->A = - (c->P * c->r * pow(1.0 + c->r, (double)(c->n - c->k)));
-		c->A = c->A / (1.0 - pow(1.0 + c->r, (double)(c->n - c->k)));
+		if (c->r == 0.0) {
+			c->A = c->P / c->n;
+		} else {
+			tmp = pow(1.0 + c->r, (double)(c->n - c->k));
+			c->A = - (c->P * c->r * tmp);
+			c->A = c->A / (1.0 - tmp);
+		}
 	}
 	c->k++;
 	c->I = c->r * c->P;