How to write the Nim version of a C function pointer and pass it as argument to C function

[TKD]

Can I ask another question relating to double pointers.

Given the following C function:
    
    
    int calc_jac(double y[], double** jac)
    {
        double r = 6.0e7 * y[0];
        jac[1][0]  = r;
        jac[0][0] = -0.04 - 1.0e4 * y[1] - r
        jac[0][1] = -0.04 - 1.0e4 * y[0]
        jac[1][1] = 0.0
        return 1
    }
    
    
    Run

My Nim equivalent for the declaration is:
    
    
    proc calcJac(y: ptr UncheckedArray[cdouble], jacobian: ptr 
UncheckedArray[ptr cdouble])
    
    
    Run

  1. Is this correct?
  2. How do I write the complete function in Nim as in how do I assign values 
to the matrix elements?