# Mathematical notation to multiply matrix elements

#### DyslexicHobo

Hi all,

I need to figure out the mathematical notation to multiply matricies A and B = C so that...

If matrix A is...
a1
a2
a3
a4
a5

and matrix B is...
b1
b2
b3
b4
b5

so that matric C is...
a1*b1
a2*b2
a3*b3
a4*b4
a5*b5

Would this involve using a the transverse of a matrix?

Thanks.

#### CRGreathouse

Homework Helper
Looks like the componentwise multiplication of vectors to me.

#### Mark44

Mentor
That is, the dot product of two vectors.

#### DyslexicHobo

When I calculate the doct product of those two matricies, won't I get a single scalar value?

#### DyslexicHobo

Okay, I found what I was looking for. It's called a Hadamard product. The Hadamard product A and B produces matrix C so that C_i,j = A_i,j * B_i,j.

Is there any way to compute this using common mathematical operators (such as inverse, transpose, dot product, cross product)?

The reason I ask is because I'm doing a homework assignment in Mathcad calculating power requirements of a car at certain speeds. I'm just assigning the speeds to a single-column matrix and the resistant forces to a single-column matrix. I want to output a power matrix.

If I can't figure it out, I'll just have to manually assign a force and velocity variable to each speed, but there must be a way to do this more easily.

#### Fredrik

Staff Emeritus
Gold Member
I don't know what Mathcad is, but in Matlab you would write this sort of multiplication as .* instead of just *. (That last period just ends the sentence of course).

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