# Matrix multiplication using W|A ?

**URL:** <https://community.wolfram.com/t/matrix-multiplication-using-w-a/13465>\
**Category:** Questions\
**Tags:** wolfram-alpha, algebra\
**Created:** [December 20, 2018, 10:14am UTC](https://community.wolfram.com/t/matrix-multiplication-using-w-a/13465 "2018-12-20T10:14:24Z")\
**Posts on this page:** 5\
**Page:** 1

<div class="post-metadata">

**Author:** ![denisporplenko](https://avatars.discourse-cdn.com/v4/letter/d/ec9cab/32.png) [@denisporplenko](https://community.wolfram.com/u/denisporplenko)\
**Post date:** [December 20, 2018, 10:14am UTC](https://community.wolfram.com/t/matrix-multiplication-using-w-a/13465/1 "2018-12-20T10:14:24Z")

</div>

I try to compute matrix multiplication for matrix with entries likes 1/sqrt(2)  
But any my tries finished with error (wolfram can not understand me…)  
I tried in W|A:

```
{{1/Sqrt[2]}, {1/Sqrt[2]}}.{{1/Sqrt[2], 1/Sqrt[2],0}}

```

I need matrix 1x3  
but 3x1 is correct  
`{{1/Sqrt[2], 1, 2}}`

Please give me some idea about it

---

<div class="post-metadata">

**Author:** ![hdolhaine](https://yyz1.discourse-cdn.com/wolfram/user_avatar/community.wolfram.com/hdolhaine/32/35924_2.png) [@hdolhaine](https://community.wolfram.com/u/hdolhaine)\
**Post date:** [December 20, 2018, 11:28am UTC](https://community.wolfram.com/t/matrix-multiplication-using-w-a/13465/2 "2018-12-20T11:28:55Z")

</div>

What exactly is your problem? Your post is not understandable!

---

<div class="post-metadata">

**Author:** ![anon21378091](https://avatars.discourse-cdn.com/v4/letter/a/bcef8e/32.png) [@anon21378091](https://community.wolfram.com/u/anon21378091)\
**Post date:** [December 20, 2018, 2:36pm UTC](https://community.wolfram.com/t/matrix-multiplication-using-w-a/13465/3 "2018-12-20T14:36:51Z")

</div>

Ok  
I want to compute

```
{{1/Sqrt[2]}, {1/Sqrt[2]}}.{{1/Sqrt[2], 1/Sqrt[2],0}}

```

but Wolfram says me \*\*wrong dimensions \*\*  
I want to compute 2_1 . 1_3 matrices

---

<div class="post-metadata">

**Author:** ![denisporplenko](https://avatars.discourse-cdn.com/v4/letter/d/ec9cab/32.png) [@denisporplenko](https://community.wolfram.com/u/denisporplenko)\
**Post date:** [December 20, 2018, 2:39pm UTC](https://community.wolfram.com/t/matrix-multiplication-using-w-a/13465/4 "2018-12-20T14:39:00Z")

</div>

Ok I want to compute

```
{{1/Sqrt[2]}, {1/Sqrt[2]}}.{{1/Sqrt[2], 1/Sqrt[2],0}}

```

but Wolfram says me wrong dimensions I want to compute  
`2*1 \cdot 1*3 matrices`

* * *

---

<div class="post-metadata">

**Author:** ![danl](https://yyz1.discourse-cdn.com/wolfram/user_avatar/community.wolfram.com/danl/32/41267_2.png) [@danl](https://community.wolfram.com/u/danl)\
**Post date:** [December 20, 2018, 2:58pm UTC](https://community.wolfram.com/t/matrix-multiplication-using-w-a/13465/5 "2018-12-20T14:58:54Z")

</div>

Woiks for me.

```
In[3]:= {{1/Sqrt[2]}, {1/Sqrt[2]}}.{{1/Sqrt[2], 1/Sqrt[2], 0}}

Out[3]= {{1/2, 1/2, 0}, {1/2, 1/2, 0}}

```