Improve error handling of Steps, Stats, and Step.

Fixes #19

Author: halirutan

README.md

@@ -14,12 +14,14 @@ integration step.
 
 ## Documentation
 
-The main documentation of the Rubi project can be found under [rulebasedintegration.org](https://rulebasedintegration.org).
-Certain development specific information about this Mathematica package will be made available in the [Rubi GitHub Wiki](https://github.com/RuleBasedIntegration/Rubi/wiki).
-Since the Wiki is at the moment not complete, please visit the [current Rubi website](http://www.apmaths.uwo.ca/~arich/).
-
+The user documentation of the Rubi project can be found under [rulebasedintegration.org](https://rulebasedintegration.org).
 For an installation- and usage-guide, please see the [Mathematica Package](https://rulebasedintegration.org/mathematicaPackage.html) section on [rulebasedintegration.org](https://rulebasedintegration.org).
 
+
+Certain development specific information about this Mathematica package can be found in the [Rubi GitHub Wiki](https://github.com/RuleBasedIntegration/Rubi/wiki).
+There, you will also find how you can contribute to the project.
+Since the Wiki is at the moment not complete, please also visit the [current Rubi website](http://www.apmaths.uwo.ca/~arich/).
+
 ## Repository structure and development
 
 ### General

Rubi/PacletInfo.m

@@ -5,7 +5,7 @@
 
 Paclet[
   Name -> "Rubi",
-  Version -> "4.16.0.4",
+  Version -> "4.16.0.5",
   MathematicaVersion -> "9+",
   Description -> "Package for Rule-based Integration",
   Creator -> "Albert D. Rich, Patrick Scheibe",

Rubi/Rubi.m

@@ -318,7 +318,8 @@
 Options[Steps] = {
   RubiPrintInformation -> True
 };
-Steps[expr_Int, opts : OptionsPattern[]] := Steps[expr, $IterationLimit, opts];
+Int::wrngUsage = "Wrong usage of the `1` function. Please use `1`[Int[expr, x]].";
+Steps[Int[expr_, x_], opts : OptionsPattern[]] := Steps[Int[expr, x], $IterationLimit, opts];
 Steps[Int[expr_, x_], n_Integer, OptionsPattern[]] := Module[{result, steps},
   If[$LoadShowSteps =!= True,
     Message[Int::noShowSteps];
@@ -341,6 +342,7 @@
     {steps, result}
   ]
 ] /; Head[x] === Symbol && If[TrueQ[n > 0], True, Message[Steps::negSteps]; False];
+Steps[___] := (Message[Int::wrngUsage, Steps]; $Failed);
 
 SetAttributes[Step, {HoldFirst}];
 Options[Step] = {
@@ -362,6 +364,8 @@
     {step, result}
   ]
 ] /; Head[x] === Symbol;
+Step[___] := (Message[Int::wrngUsage, Step]; $Failed);
+
 
 SetAttributes[Stats, {HoldFirst}];
 Options[Stats] = {
@@ -382,6 +386,7 @@
       }
     ]
   ]] /; Head[x] === Symbol;
+Stats[___] := (Message[Int::wrngUsage, Stats]; $Failed);