In this sense, C/C++ and Python can be considered scientific programming languages.
In a stronger sense, a scientific programming language is one that is designed and optimized for the use of mathematical formula and matrices.
Scientific programming languages provide facilities to work with linear algebra.
For example, the following Julia program solves a system of linear equations: Working with large vectors and matrices is a key feature of these languages, as linear algebra lays the foundation to mathematical optimization, which in turn enables major applications such as deep learning.
Modern scientific programming languages will use automatic differentiation to compute the gradients and Hessians of the function given as input; cf.