Mathematica
Used by 7 peoplewolfram.com ↗
“For both research and art, I use Mathematica constantly.”
Clayton Shonkwiler Interview, Mathematician, animator · via Uses This 
“When a computer is necessary for calculations or to make plots, Mathematica is my first choice because that's what my students like to use.”
Chanda Prescod-Weinstein Interview, Theoretical cosmologist · via Uses This
