Finding the Dot Product of Two Vectors

The dot product (or scalar product) of two vectors is used, among other things, as a way of finding the angle theta between two vectors. Recall that, given vectors a and b in space, the dot product is defined as

a . b = | a | | b | cos( theta )

We will use this formula later to find the angle theta. For now, we want to focus on the computation formula for the dot product: given the components of the vectors a = < a1, a2, a3 > and b = < b1, b2, b3 >, the dot product is given by

a . b = a1*b1 + a2*b2 + a3*b3

Remember that in both cases, the result is NOT a vector, but a scalar (or number-hence the alternate name "scalar product").

Use this formula to write a function file which computes the dot product of two 3-dimensional vectors a and b. The function name is DotProd, which has two inputs: the vectors a and b (which should contain 3 elements each). The output is the single value y, which is a . b

NOTE: Though not assessed, it may be more efficient if you use element by element multiplication along with MATLAB's built-in command sum (which adds the components of a vector).

Your Function

function y = DotProd(a,b) % NOTE: DO NOT CHANGE THE CODE ON THIS LINE!

y = ;

end

so please can i have the Code to call my function ?

[Guillaume]

so please can i have the Code to call my function ?

No, we don't you your homework for you (particularly ones as easy as this).

See How do I get help on homework question

Answer 1

[Piyush kant]

I hope this works.

function y = DotProd(a,b)  % NOTE: DO NOT CHANGE THE CODE ON THIS LINE!
  y = a.*b ;
end  

[Guillaume]

No, it doesn't (in that it doesn't calculate a dot product at all)

In any case, don't do their homework when they have shown no effort. You're not helping them, just showing them that it's easy to cheat.

[Stephen23]

"I hope this works"

y = a.*b ;

Rather than hoping you could just read the times documentation and know that it doesn't calculate the dot product.

[Guillaume]

Or read the definition of the dot product which is given in the question (hence why this homework is so easy. The exact equation is given in the question)

[Walter Roberson]

maryam alhajji comments to Guillaume:

please respect , as the it is practice not homework , and if I know the answer I will not ask someone to help me , I am just asking for the knowledge .

[Walter Roberson]

You could read the documentation: the code for the simple case is given there.

Answer 2

[maryam alhajji]

syms a1 a2 a3 b1 b2 b3
a=[ a1 , a2 , a3];
b= [ b1 , b2 , b3];
d= dot(a,b)
c=cross (a,b)



c =
 
[ a2*b3 - a3*b2, a3*b1 - a1*b3, a1*b2 - a2*b1]

# the answer shoe me by (-) and i donot know how to keep it as

 function y = DotProd(a,b)  % NOTE: DO NOT CHANGE THE CODE ON THIS LINE!
  y =  ;
end  

# if any one can help me I am thankful .

[Walter Roberson]

Read the documentation for dot(), especially starting from "More About"