# What is the name of this letter $\mathcal{J}$?

What is the name of this letter $$\mathcal{J}$$ in the following deep learning equation? And what alphabet it is from?

$$\mathcal{J} = \frac{1}{m} \sum_{i=1}^m \mathcal{L}^{(i)}$$

• I’m voting to close this question because it seems to me that it belongs to tex.stackexchange.com. Nov 5, 2021 at 1:03

## 1 Answer

It's an uppercase "J" from the math calligraphy alphabet, i.e. \mathcal{J} in latex.

$$\mathcal{J}$$