# Potential rendering issue for formulas

when I entered the following

$$\pmb{ \frac{d_+^n}{dx_+^n}}:= \left(1, \frac{d^1}{dx^1},\,\dots,\,\frac{d^{n-2}}{dx^{n-2}},\,1\right)$$

I observed that the defined fraction has an unsharp appearance not only on MO but also on Stackedit and Typora.

Can anyone confirm my impression and maybe knows the reason and/or a fix?.

• This is by design. You are using \pmb, which stands for “poor man’s bold”, and works by typesetting several slightly offset copies of the content to give it a bolder appearance. Unsurprisingly, the results looks rather bad both in original LaTeX and in MathJax. It is meant to be used only as a last resort. Whenever possible, you should use proper bold commands such as \mathbf and \boldsymbol. – Emil Jeřábek Apr 1 at 17:20
• Thanks for the clarification; I didn't know of the meaning of pmb, I only knew of the recommendation to use it for matrices and vectors. – Manfred Weis Apr 1 at 17:38
• I don’t know who gave you that recommendation, but it is a bad one. If you want matrices and vectors in bold italic, you should use \boldsymbol (which comes from the amsmath package). There is also a dedicated package bm, but I have no experience with it. There are various questions about this topic on tex.stackexchange.com, such as tex.stackexchange.com/questions/3238/… . – Emil Jeřábek Apr 1 at 17:51
• Actually, tex.stackexchange.com/questions/199789/… tells me that bm is preferrable to \boldsymbol, which is obsolete. But anyway, \pmb should not be used. – Emil Jeřábek Apr 1 at 17:57
• I always use \bm except here on MO, where this command is not recognized. – Carlo Beenakker Apr 1 at 20:34