Delete X variable

1 files changed, 2 insertions, 4 deletions

diff --git a/dda.c b/dda.c
index 8e4d79e..f045cd4 100644
--- a/dda.c
+++ b/dda.c
@@ -72,11 +72,9 @@ dda (test_data_t *testdata)
     double dy = (y1 - y0);
     double dxdy = dx / dy;
     double yi = next_sample_y (y0);
-    double x = (yi - y0) * dxdy + x0;
     double xi = next_sample_x (x0);
-    double e = (xi - x0) * dy;
+    double e = (xi - x0) * dy - (yi - y0) * dx;
 
-    e -= (yi - y0) * dx;
     if (dx >= 0)
     {
 	while (e <= 0)
@@ -109,7 +107,7 @@ dda (test_data_t *testdata)
 	if (testdata->points[i++] != xi		||
 	    testdata->points[i++] != yi)
 	{
-	    printf ("error %f %f %f\n", x, testdata->points[i - 1], xi);
+	    printf ("error %f %f\n", testdata->points[i - 1], xi);
 	    exit (-1);
 	}