Polynomial multiplication problem SOS

[toomanystars]

Hi guys,

My multiplication algorithm is not working correctly, it keeps giving me some non sense term. Any help would be appreciated.

Thanks,

Mike

class Pol{
	
public:
	Pol(){size=0;pointer=new int[MAX];}
	Pol(const Pol& t){
		size=t.size;
		pointer=new int[size];
		for(int i=0;i<size;i++)
			*(pointer+i)=*(t.pointer+i);
	}
	~Pol(){
		delete[]pointer;
	}
	int get_longer(const int a, const int b){
		if(a>=b)return a;
		else return b;	
	}
	int get_shorter(const int a, const int b){
		if(a<=b)return a;
		else return b;
	}
	Pol& operator=(Pol& t){
		size=t.size;
		pointer=new int[size];
		for(int i=0;i<size;i++)
			*(pointer)=*(t.pointer);
		return *this;
	}
	Pol operator +(Pol& t){
		Pol sum;
		int shortest=get_shorter(t.size,size);
		int longest=get_longer(t.size,size);
		int difference=longest-shortest;
		int i;

		if(t.size<size){
			for(i=shortest;i<=difference+shortest;i++)
				t.pointer[i]=0;
		}
		else{
			for(i=shortest;i<=difference+shortest;i++)
				pointer[i]=0;
		}
		sum.pointer=new int[longest];
		sum.size=longest;
		for(i=0;i<sum.size;i++)
			*(sum.pointer+i)=*(pointer+i)+*(t.pointer+i);
		return sum;
	}
		Pol operator -(Pol& t){
		Pol sub;
		int shortest=get_shorter(t.size,size);
		int longest=get_longer(t.size,size);
		int difference=longest-shortest;
		int i;

		if(t.size<size){
			for(i=shortest;i<=difference+shortest;i++)
				t.pointer[i]=0;
		}
		else{
			for(i=shortest;i<=difference+shortest;i++)
				pointer[i]=0;
		}
		sub.pointer=new int[longest];
		sub.size=longest;
		for(i=0;i<sub.size;i++)
			*(sub.pointer+i)=*(pointer+i)-*(t.pointer+i);
		return sub;
	}
	Pol operator *(Pol& t){//problem here//gives extra nonsense term
		Pol solution;
		solution.size=t.size+size;
		solution.pointer=new int[solution.size-1];
		for(int i=0;i<t.size;i++)
			for(int j=0;j<size;j++)
				solution.pointer[i+j]=+(pointer[j]*t.pointer[i]);
		return solution;	
	}
	friend istream& operator>>(istream& in, Pol& t);
	friend ostream& operator<<(ostream& out, Pol& t);

private:
	int *pointer;
	int size;
};

int main(){

	Pol test, test1;
	cout<<"Enter first polynomial\n";
	cin>>test;
	cout<<"\nEnter second polynomial\n";
	cin>>test1;

	cout<<"\n\n"<<static_cast<char>(ALPHA)<<"(X)= "<<test<<endl;
	cout<<static_cast<char>(BETA)<<"(X)= "<<test1;

	cout<<"\n\nAddition\n";
	Pol addition=test+test1;
	cout<<static_cast<char>(THETA)<<"(X)= "<<addition;

	cout<<"\n\Subtraction\n";
	Pol subtraction=test-test1;
	cout<<static_cast<char>(OMEGA)<<"(X)= "<<subtraction;

	cout<<"\n\Multiplication\n";
	Pol multiplcation=test*test1;
	cout<<static_cast<char>(GAMMA)<<"(X)= "<<multiplcation;

	_getch();
	return 0;
}	

ostream& operator<<(ostream& out, Pol& t){
	for(int i=0;i<t.size;i++){
		if(*(t.pointer+i)>=0 && i!=0)
			out<<"+("<<*(t.pointer+i)<<"X"<<"^"<<i<<")";
		else
			out<<"-("<<abs(*(t.pointer+i))<<"X"<<"^"<<i<<")";
	}
	return out;
}
istream& operator>>(istream& in, Pol& t){
	char input[MAX];
	bool correct;
	int number;
	do{
		cout<<"Enter "<<t.size<<" co-efficient: ";
		in>>input;
		for(int i=0;i<strlen(input);i++){
			if(isdigit(input[i])){
				number=atoi(input);
				t.pointer[t.size]=number;
				t.size++;
				break;
			}
			else
				correct=false;	
		}
	}while(correct);
	return in;
}

[helios]

I doubt anyone's going to debug your broken code for you. At least tell us where you suspect the problem is, or what you expected as output and what actually came out.

[toomanystars]

Everything works fine, the only issue is with the multiplication function.

[Disch]

examples go a long long way.

Can you please give us some example input and what output it's actually producing?

I tried to run the code and check myself, but it doesn't compile as-is (MAX, BETA, GAMMA, etc are undefined)

[toomanystars]

Apologies, I forgot to cut and paste the constants

const int MAX=1000;
const int ALPHA=224;
const int BETA=225;
const int THETA=233;
const int OMEGA=234;
const int GAMMA=226;

For example, if I put in for the first pol
4
2
3
10

and for the second pol
3
5

I get

-12x^0+20X^1+10X^2+15X^3+50X^4-33686019X^5