variable.cpp

#include "variable.h"
variable::variable()
{
	coefficient = 0.0;
	powerX = 0.0;
	powerY = 0.0;
}

variable::variable(double c,double myPowerX,double myPowerY)
{
	coefficient = c;
	powerX = myPowerX;
	powerY = myPowerY;
}

variable::~variable()
{
}

variable variable::PartialDifferentiation(symbol s)
{
	variable v = variable(coefficient, powerX, powerY);

	if (s == symbol::x) {
		v.coefficient = coefficient * powerX;
		v.powerX = powerX - 1.0;

		v.zerolization();
	}
	else if (s == symbol::y) {
		v.coefficient = coefficient * powerY;
		v.powerY = powerY - 1.0;

		v.zerolization();
	}

	return v;
}

void variable::zerolization() {
	if (std::abs(coefficient) <= 1.0e-31) {
		coefficient = 0.0;
		powerX = 0.0;
		powerY = 0.0;
	}
}

bool variable::isConstant() {
	return(powerX == 0.0 && powerY == 0.0);
}

std::string variable::toString() {
	std::ostringstream strs;
	zerolization();
	if (coefficient != 0.0) {
		strs << coefficient;
	}

	if (powerX != 0.0) {
		if (powerX == 1.0) {
			strs << "x";
		}
		else {
			strs << "x^" << powerX;
		}
	}

	if (powerY != 0.0) {
		if (powerY == 1.0) {
			strs << "y";
		}
		else {
			strs << "y^" << powerY;
		}
	}

	return strs.str();
}

double variable::getValue(double x, double y) {
	double result = 1;

	if (std::abs(coefficient) < 1.0e-18) {
		return 0;
	}
	else {
		result *= coefficient;
	}

	if (std::abs(x) > 1.0e-18) {
		if (std::abs(powerX) > 1.0e-18) {
			result *= std::pow(x, powerX);
		}
	}
	else
	{
		if (std::abs(powerX) > 1.0e-18) {
			result *= 0;
		}
	}

	if (std::abs(y) > 1.0e-18) {
		if (std::abs(powerY) > 1.0e-18) {
			result *= std::pow(y, powerY);
		}
	}
	else
	{
		if (std::abs(powerY) > 1.0e-18) {
			result *= 0;
		}
	}
	//double result = coefficient * std::pow(x, powerX) * std::pow(y, powerY);

	//std::cout<< toString()<<"(" << x << "," << y << ")=" << result << std::endl;

	return result;
}