Above, enter the function to integrate. Variable of integration, integration bounds and more can be changed in "Options". Click "Go!" to start the integral/antiderivative calculation. The result will be shown further below.
How the Integral Calculator Works
For those with a technical background, the following section explains how the Integral Calculator works.
First, a parser analyzes the mathematical formula. It transforms it into a form that is better understandable by a computer, namely a tree (see figure below). In doing this, the Integral Calculator has to respect the order of operations. A specialty in mathematical formulas is that the multiplication sign can be left out sometimes, for example we write "5x" instead of "5*x". The Integral Calculator has to detect these cases and insert the multiplication sign.
Maxima takes care of actually computing the integral of the mathematical formula. Maxima's output is transformed to LaTeX again and is then presented to the user. The antiderivative is computed using the Risch algorithm, which is hard to understand for humans. That's why showing the steps of calculation is very challenging for integrals.
In order to show the steps, the calculator applies the same integration techniques that a human would apply. The program that does this has been developed over several years and is written in Maxima's own programming language. It consists of about 13000 lines of code. When the integrand matches a known form, it applies fixed rules to solve the integral (e. g. partial fraction decomposition for rational functions or trigonometric substitution for integrands involving the square roots of a quadratic polynomial). Otherwise, it tries different substitutions and transformations until either the integral is solved, time runs out or there is nothing left to try. The calculator lacks the mathematical intuition that is very useful for finding an antiderivative, but on the other hand it can try a large number of possibilities within a short amount of time. The step by step antiderivatives are often much shorter and more elegant than those found by Maxima.
If you have any questions or ideas for improvements to the Integral Calculator, don't hesitate to write me an e-mail.