Tape added

README.md

@@ -15,11 +15,11 @@ Use the `versions` configuration to specify the precision:
 * `TAUTODIFF_USE_REAL`
 ```
 // dub.sdl
-versions "TGRAD_USE_FLOAT"
+versions "TAUTODIFF_USE_FLOAT"
 ```
 ```
 // dub.json
-versions: ["TGRAD_USE_FLOAT"]
+versions: ["TAUTODIFF_USE_FLOAT"]
 ```
 
 ## Example usage
@@ -82,6 +82,48 @@ assert(solver.grad == 0);
 assert(solver.values.length == 4);
 ```
 
+### Tape
+Create `tapes` of equations and update the resulting value:
+```d
+// init
+auto tape = new Tape();
+assert(tape.values == []);
+assert(tape.values.length == 0);
+assert(tape.locked == false);
+assert(!tape.isLocked);
+
+// d = a * b - c
+auto a = 5.value;
+auto b = 10.value;
+auto c = 25.value;
+auto d = a * b;
+auto e = d - c;
+assert(e.data == 25);
+
+// push
+tape.pushBack(a);
+tape ~= b;
+tape ~= [c, d, e];
+assert(tape.values == [a, b, c, d, e]);
+assert(tape.values.length == 5);
+assert(tape.lastValue.data == 25);
+
+// lock tape
+tape.lock();
+// tape ~= 24.value; // assert error: reset the tape to push new values
+
+// modify value
+a.data = 6;
+
+// update tape
+tape.update();
+assert(tape.lastValue.data == 35);
+
+// reset tape to push new values
+tape.reset();
+tape ~= 35.value; // good
+```
+
 ### Multi-layer perceptron
 
 ```d

source/rk/tautodiff/aux/tape.d

@@ -16,7 +16,15 @@ class Tape
         locked = false;
     }
 
-    /// Retrive the last pushed value
+    /// Retreive the first pushed value
+    /// Returns: null if empty
+    Value firstValue() 
+    {
+        return values.length ? values[0] : null;
+    }
+
+    /// Retreive the last pushed value
+    /// Returns: null if empty
     Value lastValue()
     {
         return values.length ? values[$-1] : null;
@@ -44,25 +52,25 @@ class Tape
     }
 
     // Push back a single value
-    void pushBack(Value v) 
+    void pushBack(Value v) in (!isLocked, "Reset the tape to push new values.")
     {
         this.values ~= v;
     }
 
     /// Push back values
-    void pushBack(Value[] vs) 
+    void pushBack(Value[] vs) in (!isLocked, "Reset the tape to push new values.") 
     {
         this.values ~= vs;
     }
 
     /// Append a single value
-    void opOpAssign(string op: "~")(Value v)
+    void opOpAssign(string op: "~")(Value v) in (!isLocked, "Reset the tape to push new values.")
     {
         this.pushBack(v);
     }
 
     /// Append values
-    void opOpAssign(string op: "~")(Value[] vs)
+    void opOpAssign(string op: "~")(Value[] vs) in (!isLocked, "Reset the tape to push new values.")
     {
         this.pushBack(vs);
     }

source/rk/tautodiff/nn/neuron.d

@@ -3,7 +3,6 @@ module rk.tautodiff.nn.neuron;
 import rk.tautodiff.core.common;
 import rk.tautodiff.core.value;
 import rk.tautodiff.aux.activation;
-import rk.tautodiff.aux.chainsolver;
 
 class Neuron : INeuron
 {