Considering this question, actually I not remember as I must straighten square root symbol to have the classic sqrt symbol. I have used (for example),


but it not works. I not remember if I must to use \mathstrut, \smash or other....

        w_{n} = \frac{1}{N_d}\mySqrt{\frac{2\epsilon_{s}V_{bi}}{q\left( \dfrac{1}{N_a} + \dfrac{1}{N_d}\right)}}

enter image description here

Edit: 2021/11/27

Why CM font give us a ugly, sometimes, root (not slanted) instead of other fonts? What is the reason?

  • 1
    what do you mean by it doesn't work? It makes the output that you show, what do you want to change? Nov 26, 2021 at 22:23
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    the font only has sloping signs for a small range once you get to a large expression it has to be vertical as it is stretches to the size of the content by stacking vertical bits (the same as \left( ..\right) goes straight at a certain size Nov 26, 2021 at 22:28
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    You can preserve the sloping radical by replacing the \dfrac terms with inline-fraction equivalents, e.g., by replacing \left( \dfrac{1}{N_a} + \dfrac{1}{N_d}\right) with (1/N_a + 1/N_d). :-)
    – Mico
    Nov 26, 2021 at 22:31
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    @Mico Welcome in my question :-)))))))))))...yes I have understood (I think).
    – Sebastiano
    Nov 26, 2021 at 22:32
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    Does this answer your question? \sum caused \sqrt to not be slanted
    – user202729
    Nov 27, 2021 at 4:23

3 Answers 3


If your document allows using the mtpro2 math font package, you could make use of that package's \SQRT macro to get square-root symbols with sloping surds [am I using the term "surd" correctly?], as long as the total height of the argument of \SQRT does not exceed 4", or 10 cm. The formulas in your publications will never contain such a monstrosity, though, right?

enter image description here

\sqrt{\frac{2\epsilon_{s}V_{bi}}{q\left( \dfrac{1}{N_a} + \dfrac{1}{N_d}\right)}}
\SQRT{\frac{2\epsilon_{s}V_{bi}}{q\left( \dfrac{1}{N_a} + \dfrac{1}{N_d}\right)}}

With unicode-math (in LuaLaTeX or XeLaTeX), you can replace the radical symbol with any other OpenType math font’s. One of the few with a slanted radical is Garamond Math:


\setmathfont{Garamond Math}[range=\surd,

        w_{n} = \frac{1}{N_d}\sqrt{\frac{2\epsilon_{s}V_{bi}}{q\left( \dfrac{1}{N_a} + \dfrac{1}{N_d}\right)}}

New Computer Modern + Garamond Math sample

To better match the weight, I use New Computer Math Book.

  • Great ...Now I have understood the reason....."grazieeeeeeeeeeeeeeeeeeeeeeeeeee".
    – Sebastiano
    Nov 28, 2021 at 12:43

This doesn't supply a large radical symbol with a slanted stroke as requested in the question, but at the request of the OP, addresses the history of the shape in the Computer Modern fonts.

As with so many things in TeX and CM, the reason for the vertical stroke when the height exceeds a certain amount is the limited memory available when TeX was created, along with the limited capabilities of available imaging devices.

A vertical stroke can be extended easily by adding small vertical segments, which will line up automatically. Controlling the extension of a sloped line is much more complicated. It involves not only supplying a segment in the font, but also the mechanism for joining successive segments precisely. In fact, it is likely that more than one such segment, at different angles, would have to be provided, in the absence of the ability to redraw the symbol at the time of imaging. Only "static" shapes were possible when TeX was created.

  • Thank you very muchhhhhhhhhhhhhhhhhhhh +1.
    – Sebastiano
    Nov 28, 2021 at 16:26

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