diff --git a/main.cpp b/main.cpp
index 173efc05..6324aedb 100644
--- a/main.cpp
+++ b/main.cpp
@@ -41,6 +41,30 @@ public:
 	}
 };
 int main() {
+	PIEvaluator eval, eval2;
+	piCout << "start";
+
+	eval.setVariable("x", complexd(1, 2));
+	PITimeMeasurer tm;
+	eval.check("e2eelg(10ex");
+	double us = tm.elapsed_u(); piCout << "check" << us;
+
+	tm.reset();
+	PIByteArray ba = eval.save();
+	us = tm.elapsed_u(); piCout << " save" << us;
+
+	piCout << ba.size();
+
+	tm.reset();
+	eval2.load(ba);
+	us = tm.elapsed_u(); piCout << " load" << us;
+
+	//eval.setVariable("x", complexd(-2, 0));
+	eval2.setVariable("x", complexd(-2, 0));
+
+	piCout << eval.expression() << "=" << eval.evaluate();
+	piCout << eval2.expression() << "=" << eval2.evaluate();
+
 	/*A a;
 	CONNECTU(PICout::Notifier::object(), finished, &a, pcf);
 	PIString buffer = "my buff:";
@@ -177,27 +201,3 @@ int main(int argc, char *argv[]) {
 	piCout << "server" << st << ba.toHex() << ba.size();*/
 	return 0;
 }
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diff --git a/src_main/math/pievaluator.cpp b/src_main/math/pievaluator.cpp
index 72a47c24..e1754ca3 100755
--- a/src_main/math/pievaluator.cpp
+++ b/src_main/math/pievaluator.cpp
@@ -699,8 +699,8 @@ void PIEvaluator::convert() {
 
 
 
-const PIString & PIEvaluator::preprocess(const PIString & string) {
-	static PIString ret;
+PIString PIEvaluator::preprocess(const PIString & string) {
+	PIString ret;
 	int lind;
 	ret = prepare(string);
 	convert();
@@ -1180,6 +1180,7 @@ inline void PIEvaluator::execFunction(const PIEvaluatorTypes::Instruction & ci)
 
 
 inline bool PIEvaluator::execInstructions() {
+	kvars = &(content.variables);
 	PIEvaluatorTypes::Instruction ci;
 	int oi;
 	complexd tmp;
@@ -1266,3 +1267,16 @@ complexd PIEvaluator::evaluate() {
 	if (fabs(out.imag()) < 1E-300) out = complexd(out.real(), 0.);
 	return out;
 }
+
+
+PIByteArray PIEvaluator::save() const {
+	PIByteArray ret;
+	ret << content << elements << currentVariables << unknownVars << variables << instructions << currentString << lastError << out << correct;
+	return ret;
+}
+
+
+void PIEvaluator::load(PIByteArray ba) {
+	if (ba.size() <= 4) return;
+	ba >> content >> elements >> currentVariables >> unknownVars >> variables >> instructions >> currentString >> lastError >> out >> correct;
+}
diff --git a/src_main/math/pievaluator.h b/src_main/math/pievaluator.h
index d676d0c6..ce4513fe 100755
--- a/src_main/math/pievaluator.h
+++ b/src_main/math/pievaluator.h
@@ -94,6 +94,8 @@ namespace PIEvaluatorTypes {
 class PIP_EXPORT PIEvaluatorContent
 {
 	friend class PIEvaluator;
+	friend inline PIByteArray & operator <<(PIByteArray & s, const PIEvaluatorContent & v);
+	friend inline PIByteArray & operator >>(PIByteArray & s,       PIEvaluatorContent & v);
 public:
 	PIEvaluatorContent();
 	~PIEvaluatorContent() {;}
@@ -187,11 +189,17 @@ public:
 	//! Returns last result of \a evaluate()
 	const complexd & lastResult() const {return out;}
 
+	//! Save to %PIByteArray evaluator state (expression, variables, errors, compiled instructions)
+	PIByteArray save() const;
+
+	//! Restore from %PIByteArray evaluator state (expression, variables, errors, compiled instructions)
+	void load(PIByteArray ba);
+
 	PIEvaluatorContent content;
 
 private:
 	const PIString & prepare(const PIString & string);
-	const PIString & preprocess(const PIString & string);
+	PIString preprocess(const PIString & string);
 	int parse(const PIString & string, int offset = 0);
 	void convert();
 	void checkBrackets();
@@ -226,4 +234,41 @@ private:
 inline bool operator ==(PIEvaluatorTypes::Element e1, PIEvaluatorTypes::Element e2) {return (e1.type == e2.type && e1.num == e2.num);}
 inline bool operator !=(PIEvaluatorTypes::Element e1, PIEvaluatorTypes::Element e2) {return (e1.type != e2.type || e1.num != e2.num);}
 
+inline PIByteArray & operator <<(PIByteArray & s, const PIEvaluatorTypes::Instruction & v) {
+	s << ((int)v.operation) << v.operators << v.out << v.function;
+	return s;
+}
+inline PIByteArray & operator >>(PIByteArray & s, PIEvaluatorTypes::Instruction & v) {
+	int i(0);
+	s >> i >> v.operators >> v.out >> v.function;
+	v.operation = (PIEvaluatorTypes::Operation)i;
+	return s;
+}
+inline PIByteArray & operator <<(PIByteArray & s, const PIEvaluatorTypes::Element & v) {
+	s << ((int)v.type) << v.num << v.var_num;
+	return s;
+}
+inline PIByteArray & operator >>(PIByteArray & s, PIEvaluatorTypes::Element & v) {
+	int i(0);
+	s >> i >> v.num >> v.var_num;
+	v.type = (PIEvaluatorTypes::eType)i;
+	return s;
+}
+inline PIByteArray & operator <<(PIByteArray & s, const PIEvaluatorTypes::Variable & v) {
+	s << v.name << v.value;
+	return s;
+}
+inline PIByteArray & operator >>(PIByteArray & s, PIEvaluatorTypes::Variable & v) {
+	s >> v.name >> v.value;
+	return s;
+}
+inline PIByteArray & operator <<(PIByteArray & s, const PIEvaluatorContent & v) {
+	s << v.variables << v.cv_count;
+	return s;
+}
+inline PIByteArray & operator >>(PIByteArray & s, PIEvaluatorContent & v) {
+	s >> v.variables >> v.cv_count;
+	return s;
+}
+
 #endif // PIEVALUATOR_H