Question

Originally I asked: How to tranlate equations to programming instructions. Judging by the content found @ Wikipedia: Category: Equations That’s apparently too vague for simple Q&A. So I’ve deleted it.

Since I learn best by example, I would like to see what this equation looks like as a function in C.

(desired course is d, ground speed is Vg, heading is a, true airspeed is Va, wind direction is w, wind speed is Vw. d, a and w are angles. Vg, Va and Vw are consistent units of speed. \pi is 3.14159…)

The above equation is for calculating true ground speed Taken from the E6B flight computer

To be clear: I’m not asking for advice, opinions or rhetoric. I’m not asking you to do my homework. I’m asking for help to understand the process of translation from equation to functional implementation. Bear with me, I know there are quite a few aspects to be aware of in such an endeavour, I would simply like to explore the symmetry between these two symbol systems using my own knowledge, capabilities and understanding.

Due to the fact that I would like to explore the symmetry, I should ask that you keep program identifiers as closely related to their representation in the formula as possible. Key words, catch phrases and rule references pertinent to this example translation in context (code comments) are a plus.

If my question is flawed due to an OVERSIGHT, please express your opinion in the comments below.

Answer 1

To naively convert an equation into c you break it into parts based off the order of operations. Then you can refine it as needed.

The way I would break it down:

The function would have the parametres: d, w, deltaA, Va, Vw

1. Step1 = d – w + ΔA

2. Step2 = Math.PI * Step1

3. Step3 = Step2 / 180 ignore the units(deg)

4. Step4 = cos(Step3)

5. Step5 = Va * Va

6. Step6 = Vw * Vw

7. Step7 = 2 * Va * Vw

8. Step8 = Step5 + Step6 – Step7

9. Step9 = Step8 * Step4

10. Step10 = Math.sqrt(Step9)

11. Return Step10