yacas: add page (#6263)

pages/common/yacas.md

@@ -0,0 +1,28 @@
+# yacas
+
+> Yet Another Computer Algebra System.
+> More information: <http://www.yacas.org>.
+
+- Start an interactive `yacas` session:
+
+`yacas`
+
+- While in a `yacas` session, execute a statement:
+
+`{{Integrate(x)Cos(x)}};`
+
+- While in a `yacas` session, display an example:
+
+`{{Example()}};`
+
+- Quit from a `yacas` session:
+
+`{{quit}}`
+
+- Execute one or more `yacas` scripts (without terminal or prompts), then exit:
+
+`yacas -p -c {{path/to/script1}} {{path/to/script2}}`
+
+- Execute and print the result of one statement, then exit:
+
+`echo "{{Echo( Deriv(x)Cos(1/x) );}}" | yacas -p -c /dev/stdin`