DC Circuit Solver

A C++ program that solves DC circuits. It reads the circuit from a text file and prints the voltage of each node. Matrix calculations are done with the Eigen library.

Supported components

• R : resistor
• V : voltage source
• I : current source

Node 0 is ground.

Netlist file

Create a file named netlist.txt in the same folder. One component per line:

name  node+  node-  value

Example:

V1 1 0 3
V2 4 0 2
R1 1 2 2
R2 2 0 3
R3 2 3 4
R4 3 0 2
R5 3 4 1

Output:

--- Results ---
Node 1 Voltage : 3 V
Node 2 Voltage : 1.70455 V
Node 3 Voltage : 1.38636 V
Node 4 Voltage : 2 V
---------------

Install Eigen

• Mac: brew install eigen
• Ubuntu: sudo apt install libeigen3-dev
• Windows: download from the Eigen website and extract

Build and run

g++ -O2 -std=c++17 -I/opt/homebrew/include/eigen3 main.cpp -o solver
./solver

For Qt, add this line to the .pro file and run qmake:

INCLUDEPATH += /opt/homebrew/include/eigen3

Notes

• Only DC analysis, no capacitor or inductor
• The circuit must be connected to ground (node 0)
• Values must be plain numbers (10k style doesn't work)

Source Code

https://github.com/hexpad/circuit-solver/blob/main/main.cpp