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Topic: How to make Rubi show the result all the time when ShowSteps=True?
Replies: 2   Last Post: Jul 17, 2013 9:41 AM

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Nasser Abbasi

Posts: 5,694
Registered: 2/7/05
How to make Rubi show the result all the time when ShowSteps=True?
Posted: Jul 6, 2013 3:31 AM
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I am little confused by this behavior of Rubi. on some integrands,
when setting ShowSteps=True, the result of integration is not displayed
but only the rules are.

When setting ShowSteps=False and trying the same integration again,
now the final result is displayed.

Here is an example (using 4.1 on Mathematica 9.01)

--------------------------------
In[81]:= ShowSteps=True;
Int[(1-y)Sqrt[1+y]/(y Sqrt[1-y^2]),y]

During evaluation of In[81]:= Rule 17: ........

Out[82]= Int[Sqrt[1-y]/y,y] % why did it stop here?
------------------------------------

Now, repeating the same thing, but using ShowSteps=False

--------------------------------
In[83]:= ShowSteps=False;
Int[(1-y)Sqrt[1+y]/(y Sqrt[1-y^2]),y]

Out[84]= 2 Sqrt[1-y]-2 ArcTanh[Sqrt[1-y]] % now it shows !
-----------------------------------

This does not happen on all integrand. For example, on this simple one

-----------------------------
In[89]:= ShowSteps=True;
Int[Sin[x],x]

During evaluation of In[89]:= Rule 1248: ...
Out[90]= -Cos[x]
-----------------------------

The final result was given above. Same as when ShowSteps=False:

----------------------------------------
In[91]:= ShowSteps=False;
Int[Sin[x],x]

Out[92]= -Cos[x]
------------------------

So, the question is, why ShowStep=True seems to change the behavior?
Are there other setting one needs to know about?

thanks,
--Nasser



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