avoding loops by vectorization

Hello,

I am trying to rewrite a for loop by using vectors. The loop is:

for i=1:8 outer_x(i,:)=x_i(i)+d_del(1,i)*cos(t); end

where d_del is 2x8, x_i is 1x8, and cos(t) is 1x6284

The loop does the following: outer_x(1,:)=x_i(1)+d_del(1,1)*cos(t); outer_x(2,:)=x_i(2)+d_del(1,2)*cos(t); outer_x(3,:)=x_i(3)+d_del(1,3)*cos(t); etc

I tried the following: x_i(1:end)+d_del(1,(1:end))*cos(t);

I was hoping to take each entry of d_del and multiply with every entry of cos(t), but it does not work. Any help will be greatly appreciated!

[Sean de Wolski]

You say d_del = 2x8; do you use only the first row? You never access d_del(2,anything)

Answer 1

[Oleg Komarov]

outer_x = bsxfun(@plus, x_i, d_del(1,:)*cost.');

Don't use cos (i renamed it in cost) as a variable since it's already a builtin matlab function. If t is the 1 by 6284 variable then ignore my previous comment.

[Matt Fig]

I believe that lee meant to take the cosine of a vector t...

Answer 2

[Andrei Bobrov]

outer_x = bsxfun(@plus,d_del(1,:)'*cos(t),x_i');

[Sean de Wolski]

Nice Answer! :)

[Andrei Bobrov]

all +1

Answer 3

[Sean de Wolski]

outer2 = bsxfun(@plus,(d_del(1,:).')*cos(t),x_i.');

produces the same result as your loop.

[Andrei Bobrov]

O! Strong volley!

Answer 4

[Laura Proctor]

This should do it:

outer_x_new = x_i'*ones(size(t))+d_del(1,:)'*cos(t);