/sci/ - Science & Math

I can't figure that out...

I'm writing my doctoral dissertation and can't figure out if the equations are "relations" or "relationships": my native French language only has one word for it, "relations".

Say, for instance, the equation:
<div class="math">dW_{b_i} = - K_i \delta X_{b_i/ref}</div>
where <span class="math">dW_{b_i}[/spoiler] and <span class="math">\delta X_{b_i/ref}[/spoiler] are vectors and <span class="math">K_i[/spoiler] is a matrix, is it a linear relation between <span class="math">dW_{b_i}[/spoiler] and <span class="math">\delta X_{b_i/ref}[/spoiler], or a linear relationship?

Thanks for your help /sci/!

Pic sort of related, it's one of my other problems with the English language.

Why is it that USfags are still using imperial system?