Is there any build in function to perform polynomials multiplication?

Hi,

I try to find a build in function that satisfy the following:

(x1,y1)  ,  (x2,y2)

result in:

( 0  , (x1*x2) , (x1*y2) + (y1*x2) , (y1*y2) )

I did it using while loop but it is useless! it take to long time : (

Thank you

[Jan]

Claiming that the loop takes too long is not useful, when you do not post the code. Perhaps you did only forget to pre-allocate the result. In addition it is not clear if "x1" and "x2" are two variables with inconvenient names or the elements of a vector. The less the readers have to guess, the more useful will be the answers.

[Abdulatif Alabdulatif]

This is the code:

vector1 = [232,334];
vector2 = [121,523];

M = sym(1000000000000);

A1 = length(vector1);
A2 = length(vector2);
A3 = length(vector1)+ length(vector2);
result = sym(zeros(1,A3));
mult=sym(0);
index=0;

 % Set the first value of result vector to (0)

           result(1,i) = 0;

 % perform polynomials multiplication

    i=1;
    j=1;
      while i < A1+1
      while j < A2+1
        index = i + j;
          mult = sym((vector1(1,i) * vector2(1,j)));
            mult = sym(rem(mult,M));
          result(1,index) = result(1,index) + mult;
            j=j+1;
         end
             j=1;
             i = i+1;
       end

produce:

result = [0, x1, x2, x3], where x1,x2 and x3 are variables.

As I implement clustering algorithm, I have to run this code around 4000 times which takes long time.

Sorry for inconvenient explanation!

Answer 1

[Rick Rosson]

u = [ x1 ; y1 ];
v = [ x2 ; y2 ];

z = conv(u,v);

[Abdulatif Alabdulatif]

You are smart enough! ; )

Thank you