diff --git a/src/bin/main.rs b/src/bin/main.rs
index d7f518f..8aa7997 100644
--- a/src/bin/main.rs
+++ b/src/bin/main.rs
@@ -1,41 +1 @@
-fn print_bytes(bytes:&Vec<u8>)
-{
-    for b in bytes {
-        print!("{:02x} ", *b);
-    } print!("\n");
-}
-
-fn main() {
-    let a = szun::Decimal::with(32, 128.5);
-    let b = szun::Decimal::with(24, 16.0);
-    let c = a.copy() / b.copy();
-
-    println!("A      =  {} (.{})", a.get(), a.mantissa());
-    println!("B      =  {} (.{})", b.get(), b.mantissa());
-    print!("\n");
-    println!("A + B  =  {}", (a.copy() + b.copy()).get());
-    println!("A - B  =  {}", (a.copy() - b.copy()).get());
-    println!("A * B  =  {}", (a.copy() * b.copy()).get());
-    println!("A / B  =  {}", (a.copy() / b.copy()).get());
-    println!("A % B  =  {}", (a.copy() % b.copy()).get());
-    print!("\n");
-    println!("B + A  =  {}", (b.copy() + a.copy()).get());
-    println!("B - A  =  {}", (b.copy() - a.copy()).get());
-    println!("B * A  =  {}", (b.copy() * a.copy()).get());
-    println!("B / A  =  {}", (b.copy() / a.copy()).get());
-    println!("B % A  =  {}", (b.copy() % a.copy()).get());
-
-    print!("\n");
-    let out = szun::encode(*c);
-    println!("c = {}", c.get());
-    print_bytes(&out);
-    match szun::decode(&out, &mut 0) {
-        Ok(ty) => match ty {
-            szun::Type::Decimal(val) => {
-                println!("decode = {}", val.get());
-            }
-            _ => { println!("other"); }
-        }
-        Err(_) => { println!("failed"); }
-    }
-}
+fn main() { }
diff --git a/src/interface/decimal.rs b/src/interface/decimal.rs
index 4e9ac0f..e856274 100644
--- a/src/interface/decimal.rs
+++ b/src/interface/decimal.rs
@@ -76,9 +76,8 @@ impl Decimal {
 
     pub fn to_base(&self, mantissa:usize) -> Self
     {
-        let from_exp = self.mantissa();
         let mut result = Decimal::new(mantissa);
-        result.set_raw(Self::rebase(from_exp, mantissa, self.get_raw()));
+        result.set_raw(Self::rebase(mantissa, self.mantissa(), self.get_raw()));
         return result;
     }
 
diff --git a/src/interface/sparse.rs b/src/interface/sparse.rs
index cf1d18e..b03b113 100644
--- a/src/interface/sparse.rs
+++ b/src/interface/sparse.rs
@@ -3,6 +3,7 @@ use crate::runtime::{
     acquire, release,
     type_inner, type_key,
     sparse_length,
+    sparse_first, sparse_next, sparse_last,
     sparse_at, sparse_get,
     sparse_clear,
     sparse_set, sparse_unset,
@@ -38,6 +39,21 @@ impl Sparse {
         unsafe {sparse_length(self.addr)}
     }
 
+    pub fn first(&self) -> usize
+    {
+        unsafe {sparse_first(self.addr)}
+    }
+
+    pub fn next(&self) -> usize
+    {
+        unsafe {sparse_next(self.addr)}
+    }
+
+    pub fn last(&self) -> usize
+    {
+        unsafe {sparse_last(self.addr)}
+    }
+
     pub fn at(&self, index:usize) -> Reference
     {
         unsafe {sparse_at(self.addr, index)}
diff --git a/src/runtime/lib.cc b/src/runtime/lib.cc
index 21cb391..619e7b8 100644
--- a/src/runtime/lib.cc
+++ b/src/runtime/lib.cc
@@ -824,6 +824,45 @@ extern "C" void sparse_clear(Reference addr)
     rawlist_clear(list.header);
 }
 
+extern "C" size_t sparse_first(Reference addr)
+{
+    auto& list = *reinterpret_cast<Type::Sparse*>(addr.address);
+
+    if(list.header.length > 0) {
+        auto cell = reinterpret_cast<Type::SparseHeader*>(rawlist_cell(list.header, sizeof(Type::SparseHeader), 0));
+        if(cell != nullptr) {
+            return cell->start;
+        }
+    }
+    return 0;
+}
+
+extern "C" size_t sparse_next(Reference addr)
+{
+    auto& list = *reinterpret_cast<Type::Sparse*>(addr.address);
+
+    if(list.header.length > 0) {
+        auto cell = reinterpret_cast<Type::SparseHeader*>(rawlist_cell(list.header, sizeof(Type::SparseHeader), 0));
+        if(cell != nullptr) {
+            return cell->start + cell->length;
+        }
+    }
+    return 0;
+}
+
+extern "C" size_t sparse_last(Reference addr)
+{
+    auto& list = *reinterpret_cast<Type::Sparse*>(addr.address);
+
+    if(list.header.length > 0) {
+        auto cell = reinterpret_cast<Type::SparseHeader*>(rawlist_cell(list.header, sizeof(Type::SparseHeader), list.header.length - 1));
+        if(cell != nullptr) {
+            return cell->start + cell->length - 1;
+        }
+    }
+    return 0;
+}
+
 extern "C" Reference sparse_at(Reference addr, size_t index)
 {
     Reference result {0};
diff --git a/src/runtime/lib.h b/src/runtime/lib.h
index ce9f439..0289352 100644
--- a/src/runtime/lib.h
+++ b/src/runtime/lib.h
@@ -107,6 +107,9 @@ extern "C" size_t sparse_header_length(Reference addr);
 extern "C" Type::SparseHeader sparse_header_data(Reference addr, size_t index);
 extern "C" size_t sparse_length(Reference addr);
 extern "C" void sparse_clear(Reference addr);
+extern "C" size_t sparse_first(Reference addr);
+extern "C" size_t sparse_next(Reference addr);
+extern "C" size_t sparse_last(Reference addr);
 extern "C" Reference sparse_at(Reference addr, size_t index);
 extern "C" Reference sparse_get(Reference addr, size_t index);
 extern "C" void sparse_set(Reference addr, size_t index, Reference source);
diff --git a/src/runtime/mod.rs b/src/runtime/mod.rs
index 4b2264d..0114152 100644
--- a/src/runtime/mod.rs
+++ b/src/runtime/mod.rs
@@ -121,6 +121,9 @@ extern "C" {
     pub fn sparse_header_data(addr:Reference, index:usize) -> SparseHeader;
     pub fn sparse_length(addr:Reference) -> usize;
     pub fn sparse_clear(addr:Reference);
+    pub fn sparse_first(addr:Reference) -> usize;
+    pub fn sparse_next(addr:Reference) -> usize;
+    pub fn sparse_last(addr:Reference) -> usize;
     pub fn sparse_get(addr:Reference, index:usize) -> Reference;
     pub fn sparse_at(addr:Reference, index:usize) -> Reference;
     pub fn sparse_set(addr:Reference, index:usize, source:Reference);