Algebra without Fear vs iDroidSim

The Algebra without Fear app helps you gain confidence in your basic algebra skills. The app generates an unlimited number of problems of various types, so you can practice: •Solving word problems. •Solving linear equations. •Solving linear equations by Completing the Square. •Finding the greatest common divisor and least common multiple of two numbers. •Finding the equation for a line. •Finding the distance between two points in the plane. •Finding the midpoint between two points in the plane. •Solving systems of linear equations in 2 variables. •Factoring quadratics. •Finding the roots of a quadratic equation using the Quadratic Formula. Each word problem includes a detailed explanation for how to construct the solution equation. The Reversed Number Problems screen, which is unique to this app, helps you learn how to identify the type of equation you need to use to solve a given word problem. The app allows you to work with numbers in the form of fractions as well as in decimal form. It comes with a built-in Calculator and a Factorizer tool (which will factor any positive integer that can be represented by 10 digits or less into its prime factors). Lots of useful information is included in the FAQ section of the app, which includes articles such as "Why Do I Have to Learn This Stuff?" and "What's the Best Way to Learn Algebra?" There is also an FYI section which contains essays that you might find interesting, such as "Is Algebra a Game?" and "Do Numbers Really Exist?".

iDroidSim is a simple and powerful circuit simulator. Perfect for students new to electronics circuit design and construction, hobbyist and tinkerers and even seasoned professionals who want a quick, handy tool to perform electronics circuit design calculations. That's interactivity and innovation you can't find in best SPICE tools for PC. iDroidSim simulator solves basic resistive circuits using Kirchoff’s Current Law (KCL) in much the same way a student in a circuits class would,the simulator systematically forms a matrix in accordance with KCL and then proceeds to solve for the unknown quantities using various algebraic techniques such as Gaussian elimination and sparse matrix techniques. For non-linear components, such as the diode and BJT ,iDroidSim engine searching for the approximate solution by making an initial guess at an answer and then improving the solution with successive calculations built upon this guess. This is called an iterative process.iDroidSim simulation uses the Newton-Raphson iterative algorithm to solve circuits with non-linear I/V relationships. For reactive elements(capacitors and inductors),the iDroidSim uses numeric integration methods to approximate the state of the reactive elements as a function of time. iDroidSim offers the Trapezoidal(I'll add a GEAR method later) integration methods to approximate the state of the reactive elements. Although for most circuits, both methods will provide almost identical results, it is generally regarded that the Gear method is more stable, but trapezoidal method is faster and more accurate. iDroidSim for now can simulate: -Resistor -Capacitor -Inductor -Potentiometer -Light Bulb -Ideal operational amplifier -Bipolar junction transistor (NPN PNP) -MOSFET N-channel depletion -MOSFET N-channel enhancement -MOSFET P-channel depletion -MOSFET P-channel enhancement -JFET N and P -PN Diode -PN Led diode -PN Zener diode -AC current source -DC current source -AC voltage source -DC voltage(battery) source -CCVS - current controlled voltage source -CCCS - current controlled current source -VCVS - voltage controlled voltage source -VCCS - voltage controlled current source -Square wave voltage source -Triangle wave voltage source -AC ampermeter -DC ampermeter -AC voltmeter -DC voltmeter -Two channe oscilloscope -SPST Switch -SPDT Switch -Voltage controlled switch -Current controlled switch -AND -NAND -OR -NOR -NOT -XOR -XNOR -JK flip-flop -7 Segment Display -D flip-flop -Relay -IC 555 -Transformer -Graetz Circuit If you are making an oscillators you have to put a small initial value on some of the reactive elements.(see the examples)