0
$\begingroup$

I have two column vecotors $A$ and $B$. I multiply all the corresponding elements of $A$ with the corresponding elements of $B$ and call the result $x$. Now I sum all the elements of $x$ and subtract the result from $B$ (from what I presume is all the elements of $B$). This result is in turn is multipled with $A$ again to give the final answer of $0$. Why is this the case? Is there a particular name to this property of vectors?

Below is a MATLAB exercise screenshot of where I am getting this particular question. $A$ is x' and $B$ is y'

enter image description here

$\endgroup$
2
  • $\begingroup$ If any mod sees this, please could you actually post the picture from the link, into the question ? I do not have enough reputation for this! $\endgroup$
    – SDG
    Nov 26, 2015 at 18:26
  • $\begingroup$ I'm sure that you have something in your notes or textbook about the dot product.... $\endgroup$
    – horchler
    Nov 26, 2015 at 20:16

1 Answer 1

0
$\begingroup$

The actions described in steps (d) and (e) are the definition of "*" in step (f)$:

$$\begin{bmatrix}x_1&x_2&\cdots&x_n\end{bmatrix}*\begin{bmatrix}y_1\\y_2\\\vdots\\y_n\end{bmatrix} := [x_1y_1 + x_2y_2 + \cdots + x_ny_n]$$

That your difference was $0$ simply tells you that you didn't goof up, and neither did the machine.

$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.