z3 is described as 'Z3 is a theorem prover from Microsoft Research' and is an app in the Education & Reference category. There are six alternatives to z3 for a variety of platforms, including Mac, Windows, Linux, Online / Web-based and Android. The best alternative is GNU Octave, which is both free and Open Source. Other great apps like z3 are R (programming language) (Free, Open Source), MATLAB (Paid), Mathematica (Paid) and fxSolver (Free).
Octave is a computer program for performing numerical computations which is mostly compatible with MATLAB. It is part of the GNU Project. It is free software under the terms of the GNU General Public License.
MATLAB is a numerical computing environment and programming language. Maintained by The MathWorks, MATLAB allows easy matrix manipulation, plotting of functions and data, implementation of algorithms, creation of user interfaces, and interfacing with programs in other languages.