Skip to main content

GSoC 2018: Week 6

Here is the brief work done for rubi in the 6th week of GSoC period.

Last week almost 70 % of the miscellaneous algebra was tested. In the start of the week, the miscellaneous algebra testing was completed. The miscellaneous algebra test cases have been pushed in this PR.

After this, I moved on to load exponential rules and test them. While loading the exponential rules, there were some parsing issues. Those were fixed. On start of the testing, it was found that some integrals depend upon the logarithmic and special_function rules. Those too needed to be loaded. There were some undefined or wrongly defined utility_functions like `CancelCommonFactors`, `Gamma (gammainc)`, `PolyGamma`, `ProductLog` and few more small functions. These didn't take much time. I fixed all these.

Soon I realised a major issue of `exp` and `Pow`. Sympy doesn't identify exp as Pow. The rubi rules are defined in such a way that exp needs to be realised as Pow. I tried to process an expression to replace exp with Pow. These are the major methods I tried :
  • Pow(E, z, evaluate=False) . This does not work well, an expression containing Mul is evaluated to exp. I tried to fix it. I found that `flatten` of Mul causes the evaluation. I found the code messy. These can be solved but requires more time.
  • Pow(Dummy('E', z, evaluate=False) .This was suggested by Aaron. The matching part has no issues in this. But functions which use the property of `E` does not work properly. Like `Log(E)` should evaluate to 1.
  • Pow(UnevaluatedExpr(E), z) . In this the matching was as expected. I modified `Log` as `return log(z).doit()` . But then also there were some issues. I made a new subclass `rubi_unevaluated_expr`. To solve the commutative issue, I defined a property in this new subclass.
I think the last one is the best solution for now. Another issue was some rules which caused recursion errors like one in the image 

To solve it I checked that if last 5 rules applied are same then return a Function `Integrate` and replace it at last while returning. This works fine.

In this week, I was unable to do much testing. But I am sure the upcoming week will be better in this respect. I have tested a small part of exponential rules. In the upcoming week, I will try to finish exponential rules within 2-3 days and soon move to logarithmic rules. 


Popular posts from this blog

GSoC 2018: Week 9

Hello everyone. Here is the progress of rubi module in the 9th week of GSoC period.
In the very beginning of the week, the PR for appelf1 was merged. My aim for this week was to load all rules and test at least a small part for each type of rule. Due to the time factor, its not possible to test all. Moreover, rubi needs to be updated to the latest version, so the test suite too will be updated.  
I started with trigo rules. They are huge in number. They were never tested before, so some utility_functions like `TrigReduce`, `KnownTrigIntegrandQ`, `FunctionOfTrig` etc were wrong. They were corrected. Soon I realised a difference between sympy and Mathematica. In mathematica, `1/Cot[x]` is automatically transformed to `Tan[x]` and `1/Tan[x]` too was transformed to `Cot[x]`. But in sympy, these are different. So, `tan(x)` didn't match to `cot(x)` . Francesco suggested to replace all `cot` with `1/tan`  and similarly for `sec` and `csc` (in the code generator too). 
Next, I moved to `i…

GSoC 2018: Week 10

Hello everyone. Here is the brief progress of Rubi module in the 10th week of GSoC period.
Last week, we were able to load all rules. Rubi has now come in a very stable and working condition. One Missing thing in the main PR was missing instructions and documentation. This week I tried my best to write instructions, so that a new user can easily get familiar with it. I have kept it really simple.
Initially, I wrote a script in Mathematica to generate downvalues in separate files. This was done till now manually, but now it's automated. Then I wrote a sympy script to generate all rules and constraints in proper files directly just by running a function. For a more easier understanding of steps, I created `` explaining all steps.
Next thing I realised that it would be good if we create a parsing script for the tests too. Till now I used maple format. But a lot of manual things were required. So I wrote a script which directly parses tests into sympy format. All this…

GSoC 2018: Week 8

Hello everyone. Here is the brief summary of the progress of rubi integration module in the 8th week of GSoC period.

We completed the testing of logarithmic test cases. Some of the tests are failing as they depend on trigonometric rules. The rules and tests have been updated in this PR.

Next, I loaded all trigonometric rules. They are huge in number. So the loading time increased from 1 min 30 sec to around 6 min. For now, I have not loaded them. I also updated the test cases for parsetools and fixed code quality issues. Currently, the travis is failing due to a bug, which has been fixed in branch 1.2. In the upcoming week, 1.2 probably will get merged in master.

Then I moved on to implementing appellf1 in sympy. Progress can be seen in this PR.

We will be updating our utility_functions to the latest version of RUBI.