diff --git a/LogarithmPlotter/qml/eu/ad5001/LogarithmPlotter/ObjectLists/ObjectCreationGrid.qml b/LogarithmPlotter/qml/eu/ad5001/LogarithmPlotter/ObjectLists/ObjectCreationGrid.qml
index 0c632e7..cf129af 100644
--- a/LogarithmPlotter/qml/eu/ad5001/LogarithmPlotter/ObjectLists/ObjectCreationGrid.qml
+++ b/LogarithmPlotter/qml/eu/ad5001/LogarithmPlotter/ObjectLists/ObjectCreationGrid.qml
@@ -42,7 +42,6 @@ Column {
     */
     function openEditorDialog(obj) {
         // Open editor
-        console.log(obj, obj.prototype)
         objectEditor.obj = obj
         objectEditor.objType = obj.type
         objectEditor.objIndex = Objects.currentObjects[obj.type].indexOf(obj)
diff --git a/LogarithmPlotter/qml/eu/ad5001/LogarithmPlotter/js/expr-eval.js b/LogarithmPlotter/qml/eu/ad5001/LogarithmPlotter/js/expr-eval.js
index 4bd6ccd..1afd66b 100644
--- a/LogarithmPlotter/qml/eu/ad5001/LogarithmPlotter/js/expr-eval.js
+++ b/LogarithmPlotter/qml/eu/ad5001/LogarithmPlotter/js/expr-eval.js
@@ -1117,7 +1117,7 @@ ParserState.prototype.parseExpression = function (instr) {
   if (this.parseUntilEndStatement(instr, exprInstr)) {
     return;
   }
-  this.parseVariableAssignmentExpression(exprInstr);
+  this.parseConditionalExpression(exprInstr);
   if (this.parseUntilEndStatement(instr, exprInstr)) {
     return;
   }
@@ -1157,37 +1157,6 @@ ParserState.prototype.parseArrayList = function (instr) {
   return argCount;
 };
 
-ParserState.prototype.parseVariableAssignmentExpression = function (instr) {
-  this.parseConditionalExpression(instr);
-  while (this.accept(TOP, '=')) {
-    var varName = instr.pop();
-    var varValue = [];
-    var lastInstrIndex = instr.length - 1;
-    if (varName.type === IFUNCALL) {
-      if (!this.tokens.isOperatorEnabled('()=')) {
-        throw new Error(qsTranslate('error', 'Function definition is not permitted.'));
-      }
-      for (var i = 0, len = varName.value + 1; i < len; i++) {
-        var index = lastInstrIndex - i;
-        if (instr[index].type === IVAR) {
-          instr[index] = new Instruction(IVARNAME, instr[index].value);
-        }
-      }
-      this.parseVariableAssignmentExpression(varValue);
-      instr.push(new Instruction(IEXPR, varValue));
-      instr.push(new Instruction(IFUNDEF, varName.value));
-      continue;
-    }
-    if (varName.type !== IVAR && varName.type !== IMEMBER) {
-      throw new Error(qsTranslate('error', 'Expected variable for assignment.'));
-    }
-    this.parseVariableAssignmentExpression(varValue);
-    instr.push(new Instruction(IVARNAME, varName.value));
-    instr.push(new Instruction(IEXPR, varValue));
-    instr.push(binaryInstruction('='));
-  }
-};
-
 ParserState.prototype.parseConditionalExpression = function (instr) {
   this.parseOrExpression(instr);
   while (this.accept(TOP, '?')) {
diff --git a/LogarithmPlotter/qml/eu/ad5001/LogarithmPlotter/js/math/common.js b/LogarithmPlotter/qml/eu/ad5001/LogarithmPlotter/js/math/common.js
index 7eeeb6b..9aabfd7 100644
--- a/LogarithmPlotter/qml/eu/ad5001/LogarithmPlotter/js/math/common.js
+++ b/LogarithmPlotter/qml/eu/ad5001/LogarithmPlotter/js/math/common.js
@@ -22,8 +22,6 @@
 .import "../utils.js" as Utils
 .import "latex.js" as Latex
 
-const DERIVATION_PRECISION = 0.1
-
 var evalVariables = { // Variables not provided by expr-eval.js, needs to be provided manually
     "pi": Math.PI,
     "PI": Math.PI,
@@ -54,10 +52,27 @@ parser.functions.integral = function(a, b, f, variable) {
     return (b-a)/6*(f(a)+4*f((a+b)/2)+f(b))
 }
 
-parser.functions.derivative = function(f, variable, x) {
-    if(f == null || variable == null || x == null)
-        throw EvalError("Usage: derivative(<function: string>, <variable: string>, <x: number>)")
-    f = parser.parse(f).toJSFunction(variable, currentVars)
-    return (f(x+DERIVATION_PRECISION/2)-f(x-DERIVATION_PRECISION/2))/DERIVATION_PRECISION
+parser.functions.derivative = function(...args) {
+    let f, target, variable, x
+    if(args.length == 2) {
+        [f, x] = args
+        if(typeof f != 'object' || !f.execute)
+            throw EvalError(qsTranslate('usage', 'Usage: %1')
+                                .arg(qsTranslate('usage', 'derivative(<function: ExecutableObject>, <x: variable>)')))
+        target = f
+        f = (x) => target.execute(x)
+    } else if(args.length == 3) {
+        [f, variable, x] = args
+        if(typeof f != 'string')
+            throw EvalError(qsTranslate('usage', 'Usage: %1')
+                                .arg(qsTranslate('usage', 'derivative(<function: string>, <variable: string>, <x: variable>)')))
+        f = parser.parse(f).toJSFunction(variable, currentVars)
+    } else
+        throw EvalError(qsTranslate('usage', 'Usage: %1 or\n%2')
+                            .arg(qsTranslate('usage', 'derivative(<function: string>, <variable: string>, <x: variable>)')
+                            .arg(qsTranslate('usage', 'derivative(<function: string>, <variable: string>, <x: variable>)'))))
+
+    let derivative_precision = x/10
+    return (f(x+derivative_precision/2)-f(x-derivative_precision/2))/derivative_precision
 }
 
diff --git a/LogarithmPlotter/qml/eu/ad5001/LogarithmPlotter/js/math/latex.js b/LogarithmPlotter/qml/eu/ad5001/LogarithmPlotter/js/math/latex.js
index b52a19e..4f25651 100644
--- a/LogarithmPlotter/qml/eu/ad5001/LogarithmPlotter/js/math/latex.js
+++ b/LogarithmPlotter/qml/eu/ad5001/LogarithmPlotter/js/math/latex.js
@@ -71,9 +71,13 @@ function parif(elem, contents) {
  * @returns {string}
  */
 function functionToLatex(f, args) {
+    console.log("Generating latex", f, args)
     switch(f) {
         case "derivative":
-            return '\\frac{d' + args[0].substr(1, args[0].length-2).replace(new RegExp(args[1].substr(1, args[1].length-2), 'g'), 'x') + '}{dx}';
+            if(args.length == 3)
+                return '\\frac{d' + args[0].substr(1, args[0].length-2).replace(new RegExp(args[1].substr(1, args[1].length-2), 'g'), 'x') + '}{dx}';
+            else
+                return '\\frac{d' + args[0] + '}{dx}';
             break;
         case "integral":
             return '\\int\\limits_{' + args[0] + '}^{' + args[1] + '}' + args[2].substr(1, args[2].length-2) + ' d' + args[3].substr(1, args[3].length-2);