# Most used mathematics for engineers?

1. Oct 7, 2012

### 5ymmetrica1

I'm thinking of applying for a degree in engineering at university next year and was wondering, what is the most commonly used mathematics that you engineers everyday in your jobs?

2. Oct 7, 2012

Trig for me.

3. Oct 7, 2012

### skeptic2

Trig, Logarithms and some complex numbers.

Last edited: Oct 8, 2012
4. Oct 7, 2012

### boneh3ad

Algebra, trigonometry, calculus/differential equations, in that order. Healthy dose of linear algebra as well.

5. Oct 8, 2012

### skeptic2

Matrices, for finding currents and voltages in really complex circuits.

6. Oct 8, 2012

### Pkruse

Simple arithmetic is the most common for me.

Can't get the job done without an excellent intuitive understanding of Algeria and calculus.

7. Oct 8, 2012

### boneh3ad

Man, I know almost nothing about Algeria. I've never even been there! I'm screwed! ;-)

8. Oct 8, 2012

### Studiot

Well the most common formula I have ever come across in engineering is

$$\frac{{{\rm{something}}\;{\rm{squared}}}}{{{\rm{twice}}\;{\rm{something}}\;{\rm{else}}}}$$

This comes from expanding all sorts of more complicated formula in a series and taking the first term.

For example the deviation of a circular curve from a straight line is

$$\frac{{{\rm{length}}\;{\rm{along}}\;{\rm{tangent}}\;{\rm{squared}}}}{{{\rm{twice}}\;{\rm{radius}}}}$$

There are many others

So I've got to say study series and how to sum them.

9. Oct 8, 2012

### 5ymmetrica1

thats interesting to know, thanks for sharing

seems trig is the common answer, which is what I would have thought would be most useful for engineers.
any more specific formulas that you engineers use everyday?

10. Oct 9, 2012

### Studiot

Here is another example of my formula which demonstrates engineering thinking.

Engineering drawings give vertical and horizontal distances.
Slope distances are rarely offered.

If you are measuring between two points with a tape measure your tape will indicate the difference in slope length (S). This is different from the horizontal length L, due to the difference in vertical height H.

Now H, L and S are connected by pythagoras theorem since they form a right angled triangle

$${S^2} = {L^2} + {H^2}$$

A bit of rearrangement and application of the binomial theorem gives, as a series

$$\frac{L}{S} = \sqrt {1 - \frac{{{H^2}}}{{{S^2}}}} = 1 - \frac{{{H^2}}}{{2{S^2}}} - \frac{{{H^4}}}{{8{S^4}}}$$

If we only take the first two terms of the series we obtain

$$S - L \approx \frac{{{H^2}}}{{2{S^2}}}$$

Which is the correction to be subtracted from the distance measured on the tape to obtain the correct horizontal distance.

Last edited: Oct 9, 2012
11. Oct 10, 2012

### Vadar2012

Yeah Studiot, I was surprised to see that pattern when doing a lot of dimensional analysis. Lift coefficient for example.

12. Oct 10, 2012

### 5ymmetrica1

thanks for the example studiot! I've actually just finished highschool so I've just done 2 years of similar problems to your example. Its cool to see that what I've already studied is still used commonly in engineering (which I hope to study in the near future)

13. Oct 10, 2012

### Studiot

Good luck and go well in your future studies.

Remember, members may change but PF will be here for you.

14. Oct 10, 2012

### Enthalpy

Maths... That's very variable! Most time it's nothing more than polynoms and linear algebra, plus simple summing.

But if you're an electrical engineer and make error-correcting codes, it's Galois fields all the day. Not complicated, but very different from the rest.

If you make antennas or optics or radiocomms it's interferences and Fourier transform and convolutions. Plus Laplace transform. Complex numbers of course, why mention it.

And recently I had to train again calculus, differential equations and such things to compute a surface temperature when receiving a constant power (not a constant temperature) beginning at t=0 (in this case it was for a brake). It took me one full week for a single equation, but my company badly needed it.

If you make images with X-rays and the like, you need statistics. More often than that in fact.

You see? It's varied, it's a lot, and it's a big effort for a short use. But on the other hand, you can't predict what you will need, and far less what your job will be in 20 years, as most engineers change their activity several times in a carreer. So I would say: learn as much as you can when you have this opportunity! Learning later is harder and more expensive.

15. Oct 10, 2012

### huntoon

Enthalpy has good advice.

16. Oct 16, 2012

### FrankvdW

You can see at a glance that the result of 'studiot' is not correct. On the left side the dimension is 'meter', while on the right side the dimension is 'none'. The correct formula is:
S - L ≈ H*H/(2*S) or, preferable, S - L ≈ H*H/(2*L).

17. Oct 16, 2012

### Studiot

Yes well spotted Frank, thank you for noting the superfluous squaring of the term on the bottom.

I do have trouble trying to get the formula right and the latex right at the same time and sometimes they get muddled up.

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