Change time to use i64 instead of u64

src/batch.rs

@@ -9,7 +9,7 @@ pub(crate) struct Skill {
     pub(crate) forward: Gaussian,
     backward: Gaussian,
     likelihood: Gaussian,
-    pub(crate) elapsed: u64,
+    pub(crate) elapsed: i64,
     pub(crate) online: Gaussian,
 }
 
@@ -57,7 +57,7 @@ impl Event {
 pub struct Batch {
     pub(crate) events: Vec<Event>,
     pub(crate) skills: HashMap<Index, Skill>,
-    pub(crate) time: u64,
+    pub(crate) time: i64,
     p_draw: f64,
 }
 
@@ -66,7 +66,7 @@ impl Batch {
         composition: Vec<Vec<Vec<Index>>>,
         results: Vec<Vec<f64>>,
         weights: Vec<Vec<Vec<f64>>>,
-        time: u64,
+        time: i64,
         p_draw: f64,
         agents: &mut HashMap<Index, Agent>,
     ) -> Self {
@@ -444,10 +444,10 @@ impl Batch {
     }
 }
 
-pub(crate) fn compute_elapsed(last_time: u64, actual_time: u64) -> u64 {
-    if last_time == u64::MIN {
+pub(crate) fn compute_elapsed(last_time: i64, actual_time: i64) -> i64 {
+    if last_time == i64::MIN {
         0
-    } else if last_time == u64::MAX {
+    } else if last_time == i64::MAX {
         1
     } else {
         actual_time - last_time