# How can we set \displaystyle for a whole text?

Since there is no preamble to set \displaystyle for the whole text, how can we do to avoid writing \displaystyle each time we write a new formula?

(but I still want to write inline)

For example if I want to write this :

$$\sum\limits_{k=1}^{n} u_k$$ is ... so we have $$\sum\limits_{k=1}^{n} u_k ^2 = ...$$, and it implies that $$\sum ...$$. but I don't want to write \displaystyle each time.

• Ummm, use $$<content>$$ Dec 27 '20 at 15:53
• Yes but I want to write inline.
– math
Dec 27 '20 at 16:02
• This seems a bit unusual to me. What are actually the places where you need displaystyle? Do you need it for limits/integrals? Or do you want to have bigger fractions? Dec 27 '20 at 16:13
• Actually both : mostly when i use sums and integrals
– math
Dec 27 '20 at 16:14
• $\displaystyle{........................................................}$ Dec 27 '20 at 16:20
• But please, @math, do not use display style in titles! Dec 27 '20 at 16:21
• yes i know about that, thank you @amWhy, i edited my question to be clearer
– math
Dec 27 '20 at 16:23

2. You shouldn't do this, anyway. Display style mathematics really ought to be reserved for displayed equations and expressions. Putting display style mathematics inline monkeys with line spacing, and creates a rather inconsistently typeset document. $$\sum_{k=1}^{n} u_k$$ is correct. $$\sum\limits_{k=1}^{n} u_k$$ really isn't (note how it stretches the interline-spacing).