# Revised Library of Functions for “A Virtual Analog Computer for Your Desktop”

## Description

Analog computing has received increased attention in recent years because of extremely high processing speeds at very low energy cost [1]. In addition to being fun to use, analog computers are excellent teaching tools for solving differential equations. As explained by Arthur Glazar, analog computers became extinct in the 1970s for good reasons, but the reasons for the demise are eliminated in a virtual implementation [2]. Analog computers continue to find applications in niche computing applications. For example, in automatic process control, analog representations allow very clear visualization of the flow of information through the control network. Analog signal processing is also still common in other applications such as instrumentation for process or chemical analysis. The files provided here allow the user to explore and learn the basics of analog computing in the LTspice environment. Revised Library of Functions is an update to the library originally published by Arthur Glazar [2]. The original starter library of functions was published simultaneously Steve Taranovich [3]. The original library contains basic operators for use in LTspice electronic simulation software [4]. LTspice is a high-performance SPICE simulator, schematic capture and waveform viewer with enhancements and models for the simulation of analog electronic circuits [3]. Glazar's library includes operators for integration, differentiation, summation, inversion, multiplication, and division. The original version was for LTspiceIV, and the original files still work in LTspiceXVII. However, the original “3Summer” file contained an error which needs to be fixed before the operator can be used. That file has been corrected here. That and the other files have also been updated and simplified for easier use in the Windows 10 operating system.

## Files

## Steps to reproduce

The original article by Glazar includes the time-domain solution to a 10-volt step change in the supply voltage of an RCL circuit having a capacitance of 1 microfarad, an inductance of 0.01 henry, and a resistance of 10 Ohms. The solution schematic and actual output data are in Figures 6 and 7 of the original article. The LTspice file associated with Figure 6 is also included with the downloadable files. For the update, as each operator was revised, it was substituted into the schematic and the process re-run to verify that the solution data is exactly identicl to the previously published version.