diff --git a/src/init.c b/src/init.c
index e7c51a7..7a7426f 100644
--- a/src/init.c
+++ b/src/init.c
@@ -132,7 +132,9 @@ static void refine_interval(double xl, double xr, double yl, double yr, double r
   return ;
 }
 
-int init(double bmax, double rela_err_limit){
+int init(double bmax, double rela_err_limit, int *size, double *x, double *y){
+  if (x) free(x);
+  if (y) free(y);
   SampleData sample;
   sample.capacity = 1;
   sample.size=1;
@@ -151,8 +153,13 @@ int init(double bmax, double rela_err_limit){
   //output
   //printf("Total sample points capacity: %d\n", sample.capacity);
   //printf("Total sample points number: %d\n", sample.size);
+  *size = sample.size;
+  x = malloc(sizeof(double) * sample.size);
+  y = malloc(sizeof(double) * sample.size);
   for (int i = 0; i < sample.size; i++) {
-    printf("%.16g %.16g\n", sample.x[i], sample.y[i]);
+    //printf("%.16g %.16g\n", sample.x[i], sample.y[i]);
+    x[i] = sample.x[i];
+    y[i] = sample.y[i];
   }
 
   free(sample.x);