Commits on Aug 12, 2022

1. Add Support for Functions with Constant Array Type Parameters in Jaco… …

   …bian Mode
   
   Now One must be able to find the Jacobian of functions with Constant Arrays in the parameter list.
   For example, a function of the form:
   ```cpp
   void func(double arr[3], double x, double y, double* output){
   	output[0]=arr[2]*x*y;
   	.
   	.
   	.
   	output[n-1]=arr[0]*arr[1]*arr[2];
   }
   ```
   
   will generate a Jacobian of size n x 5.
   
   Corresponding tests for the same have been written.
   
   Previously this feature was not implememnted because it was necessary to know the size
   of an array to correctly determine the size of the output jacobian matrix. This has now
   been achieved for constant arrays, as we know the array sizes for them and hence we can
   precisely locate where each jacobian entry for a array parameter is located. This is
   achieved with the help of m_IndependentVarsSize, which stores the number of actual parameters
   that each function parameter corresponds to.
   
   Prior to this commit a std::map<ValueDecl, Expr> was used to map variable declarations to
   their corresponding jacobian expression, so that we can lookup the latter during the reversemode
   computations quickly. While this is fine for primitive variables(because each variable will only
   correspond to one jacobian expression), an array declaration will correspond to multiple jacobian
   expressions, depending on which index of the array is being referred to. Since the ValueDecl can
   only refer to the name of the array and not name+index, we must update the map to use the name of
   the array + index as the key. This can be done easily by using a string representation of the
   ValueDecl name with the index as a suffix as the key of the map. Hence variables like
   m_ExprVariables, m_VectorOutputString have been introduced to map array declarations, indexed by
   position in array to their corresponding jacobian expressions.
   
   Closes vgvassilev#472

   

   Nirhar committed Aug 12, 2022
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