Yacas Download
Dibe Naro
There are two R packages for yacas. Some references online refer to the old package. Some old commands are still useful just make sure we have downloaded the old package. Also, we cannot use the yacas commands on the official manual directly with R interface. We have to do something like yacas("...") or some yacas commands specifically for R.
==> Starting build()...==> ### cmake-- The CXX compiler identification is GNU 11.1.0-- The C compiler identification is GNU 11.1.0-- Detecting CXX compiler ABI info-- Detecting CXX compiler ABI info - done-- Check for working CXX compiler: /usr/bin/c++ - skipped-- Detecting CXX compile features-- Detecting CXX compile features - done-- Detecting C compiler ABI info-- Detecting C compiler ABI info - done-- Check for working C compiler: /usr/bin/cc - skipped-- Detecting C compile features-- Detecting C compile features - done-- Found Sphinx: /usr/bin/sphinx-build
-- Found UnixCommands: /usr/bin/bash
-- Configuring done-- Generating done-- Build files have been written to: /home/user/.cache/yay/yacas/src/yacas-1.9.1/build==> ### make[ 1%] Building HTML documentation with SphinxWARNING: html_static_path entry '_static' does not exist
That is correct @bokaila, qt5-svg and other dependencies were missing in this new version of yacas, are already corrected.I delayed in correcting them because with the latest update of Sphinx* the compilations gave error, with all the updates of today I can see that the PKGBUILD works well.
In addition to rearranging formulas, we can use Ryacas to derive functions. Last year I showed how to use the Deriv package to calculate the derivative of a function in R. Those formulas only had one variable to worry about. This utility function has two, which means we need to take the partial derivative with respect to \(x\) (\(\partial u / \partial x\)) and divide it by the partial derivative with respect to \(y\) (\(\partial u / \partial y\)).
From my minimal tinkering, neither the base R derivative functions nor Deriv::Deriv() can handle partial derivatives well, but Ryacas::deriv() does. Also, since it returns expressions, we can do math (like division!) with the partial derivatives. Here I find each of the partial derivatives and then use Simplify() to clean up their ratio:
Installation should be rather painless. On Linux you need to install Yacas first, which should be available in the major distros' repositories. Then you can install Ryacas from within the R shell. On Windows, you need to run these three commands (don't bother installing Yacas first):
While it has some flaws, Ryacas can be quite useful if you need to derive or integrate complicated expressions that you then want to use in R. Using some of the tricks I showed here, you should be able to overcome some of its shortcomings. If installation of rJava and thus rSympy becomes easier, I'll probably also do a short blog-post about it, as it has more features than Ryacas.
It also means that the API has changed in Ryacas: new functions are introduced and old ones deprecated.Before showing the new API, let us first mention that a legacy version of Ryacas is available at GitHub. We call it Ryacas0.
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