PSpice is best suited for electrical engineers, educators, and students in electronics engineering, as well as professionals involved in circuit design, testing, and analysis who need reliable simulation tools to validate their designs.
Scilab is recommended for engineers, scientists, and educators who require a powerful computational tool without the associated costs of commercial software. It is also suitable for students and researchers who are looking to perform complex mathematical modeling and simulations.
Solve Elec - Solve Elec is a free educational program to draw and analyze electrical circuits.
MATLAB - A high-level language and interactive environment for numerical computation, visualization, and programming
LTspice - LTspice® is a high performance SPICE simulation software, schematic capture and waveform viewer with enhancements and models for easing the simulation of analog circuits.
Wolfram Mathematica - Mathematica has characterized the cutting edge in specialized processing—and gave the chief calculation environment to a large number of pioneers, instructors, understudies, and others around the globe.
Oregano - oregano - An electrical engineering tool for GNOME
GNU Octave - GNU Octave is a programming language for scientific computing.