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waht

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**Introduction:**

WolframAlpha is a freely available computational engine that can supplement already existing software such as mathematica, maple, mathlab, or excel. The purpose of this mini-guide is to go over some of its functionality with emphasis on electrical engineering.

www.wolframalpha.com

Dimensional analysis:

Dimensional analysis:

WolframAlpha recognizes many common units. It will simplify dimensions and scale units. For example,

Code:

`farad * henry`

Code:

`0.01 uF to pF`

WolframAlpha also can tap its database to pull up a conversion formula from the context

Code:

`convert 25 MHz to meters`

Code:

`find energy in 100 uF at 10 KV`

or to find inductance to resonate with 10 nF capacitor at 100 Khz; just say that

Code:

`find inductance for 10 nF at 100 KHz`

Also if you haven't memorized resistor color bands already, you can still look them up

Code:

`resistor yellow purple red`

output: 4.7K

**Complex numbers and phasors:**

Working in polar form is supported in W|A. By typing an impedance in rectangular form

Code:

`30 + 45i`

and likewise, we can indicate a phasor in polar form with an exponential e

Code:

`e^(i pi)`

we can also manipulate phasors algebraically

Code:

`100 e^(i 45 deg) + 25 e^(i 30 deg)`

indicate degrees with “deg” otherwise W|A will interpret it in radians.

**Solving equations:**

To solve [itex] x^2 - 2x + 1= 0[/itex], enter the equation as it is

Code:

`x^2 - 2x + 1 = 0`

and W|A solves it. Don't even have to specify the variable to be solved.

Solving systems of equations is just as easy,

[tex] v_1 + v_2 + v_3 = 4 [/tex]

[tex] v_1 - v_2 = 10 [/tex]

[tex] v_1 - 3v_2 + 5v_3 = 8 [/tex]

simply type

Code:

`v1 + v2 + v3 = 4, v1-v2 = 10, v1 - 3v2 + 5v3 = 8`

just make sure that the equations are separated by a comma.

Differential equations are supported as well. An nth number of apostrophes indicates an nth derivative, and proceed as before. For example to solve

[tex] \frac{d^2y}{dx^2} - \frac{dy}{dx} - 2y = 0 \indent y(0) = 1, y'(0) = 2 [/tex]

enter the code as follows,

Code:

`y'' – y' - 2 y = 0, y(0) = 1, y'(0) = 2`

We can also maximize and minimize

Code:

`max 1 - x^2`

**Logic gates and boolean algebra:**

Converts number bases,

Code:

`binary 1111101 to hex`

We can also work with boolean expression in WolramAlpha, for example

Code:

`(x or y) and (x or !y)`

http://img200.imageshack.us/img200/9384/truthtable.gif [Broken]

a schematic with logic gates, and even simplifies the expression to a minimal form

http://img268.imageshack.us/img268/3233/scehmatic.gif [Broken]

Here is the supported syntax:

Code:

```
NOT = !
OR = ||
AND = &&
NAND
NOR
XOR
```

**More on calculus:**

W|A can perform basic calculus

take derivatives:

[tex] \frac{d}{dt} cos(t) [/tex]

Code:

`derivative cos(t)`

do integration:

[tex] \int \frac{1}{x+1} dx [/tex]

Code:

`integrate 1/(x+1) dx`

and take Laplace and Fourier transforms:

[tex] \mathcal{L}(x^2), \mathcal{F}(e^x) [/tex]

Code:

`laplace x^2`

Code:

`fourier e^x`

**Plotting:**

If you want to graph a transfer function for instance,

[tex] H(s) = \frac{s+10}{s^2 + 4s + 8} [/tex]

enter:

Code:

` graph (s + 10)/(s^2 + 4s + 8)`

and here we have

http://img32.imageshack.us/img32/9715/graph.gif [Broken]

**Conclusion:**

WolframAlpha uniquely combines different tools into a one freely available package and that expands our tool box. This mini-guide doesn't cover all of W|A, it merely touches upon features that can be used in electrical engineering, for more information visit their examples page

http://www28.wolframalpha.com/examples/

also, W|A is said to expand in the future, enabling more functionality, and tools.

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