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buchmann |
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#include <iostream>
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#include <TMath.h>
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using namespace std;
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/*
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*
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* This file contains the class "Unit", the version is 1.0
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* This class stores the value and error of a given parameter and is able to perform error propagation for addition, subtraction, multiplication, division and even powers. Please add any bugs you find to the change log below.
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*
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* V1.0
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* - First implementation with operators +,-,*,/ and pow; also implemented a custom "<<" operator (i.e. overloaded it)
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*
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*/
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class Value
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{
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float value;
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float error;
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public:
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Value(float value, float error);
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float getValue();
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float getError();
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Value operator+(const Value& c);
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Value operator-(const Value& c);
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Value operator/(const Value& c);
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Value operator*(const Value& c);
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Value Pow(Value a, Value b);
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};
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Value::Value(float newvalue = 0, float newerror = -999) : value(newvalue) {
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if(newerror!=-999) {
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error=newerror;
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} else {
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error = TMath::Sqrt(newvalue);
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}
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}
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float Value::getValue()
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{
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return value;
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}
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float Value::getError()
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{
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return error;
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}
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Value Value::operator+(const Value& c)
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{//verified
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Value result;
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result.value = (this->value+c.value);
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result.error = TMath::Sqrt((this->error)*(this->error)+(c.error)*(c.error));
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return result;
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}
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Value Value::operator-(const Value& c)
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{//verified
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Value result;
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result.value = (this->value-c.value);
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result.error = TMath::Sqrt((this->error)*(this->error)+(c.error)*(c.error));
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return result;
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}
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Value Value::operator*(const Value& c)
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{//verified
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Value result;
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result.value = (this->value*c.value);
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result.error = TMath::Sqrt(c.value*c.value*(this->error)*(this->error)+(this->value)*(this->value)*(c.error)*(c.error));
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return result;
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}
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Value Value::operator/(const Value& c)
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{//verified
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Value result;
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result.value = (this->value/c.value);
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result.error = TMath::Sqrt((1/(c.value*c.value))*(this->error)*(this->error) + ((this->value/(c.value*c.value))*(this->value/(c.value*c.value)))*(c.error*c.error));
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return result;
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}
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Value Value::Pow(Value a, Value b)
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{
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//this calculates e.g. sqrt(a), where b=(0.5,0)
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Value result;
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result.value = TMath::Power(a.value,b.value);
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result.error=TMath::Power(a.value,b.value)*TMath::Sqrt(TMath::Power(a.value,-2)*(b.value-1)*(b.value-1)*(a.error*a.error)+(TMath::Log(a.value)*TMath::Log(a.value))*(b.error*b.error));
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return result;
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}
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std::ostream &operator<<(std::ostream &ostr, Value v)
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{//this leads to an output like 2.000 +/- 1.000
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return ostr << v.getValue() << " +/- " << v.getError();
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}
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/*
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int main()
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{
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cout << "This is my value class" << endl;
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Value a(2,2);
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Value b(16,7);
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Value sq(0.5);
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Value c = a/b;
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Value d = d.Pow(b,sq);
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cout << c << endl;
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cout << "log 11 " << TMath::Log(11) << endl;
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cout << "Power: " << d << endl;
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return 0;
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}
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*/ |
