/*
 *  hw3harness.h
 *  
 * I WILL OVERWRITE YOUR COPY OF THIS FILE WITH MY OWN. ANY CHANGES YOU MAKE WILL NOT BE VISIBLE DURING GRADING.
 */
#ifndef HW3HARNESS_H
#define HW3HARNESS_H

/*
PROBLEM NOTES:
The problem that these functions generate/verify is a linear gradient with 0 on the left side and 1 on the right side. The returned b
follows this gradient.

Note that this problem doesn't converge very quickly, and in fact you may need to change your upper iteration limit in your CG solver.
Instead of limiting to sqrt(n), try 5*sqrt(n).

For larger problems you may also run into accuracy limits. If you want to verify correctly on large problems (k > 400 or so), then reduce
the norm of the residual requirement by an order of magnitude or two (add two '0' after the decimal point). 

I will actually check your residual during grading, but this problem is nice because it has a nice closed form solution.
*/

/*
Returns a single element of vector b. You may call this on any node you wish, in whatever order.
You should call this function n times.

arguments:
index - the index of the element you want. Zero based (note that Matlab is 1 based). In other words, the first element has index 0, the second index 1, etc.
int_k - k

returns:
b[index]
*/
double cs240_getB(int index, int int_k);

/*
Verifies the correctness of the CG computed on the model problem with b as returned by cs240_getB().
cs240_verify() should be called once at the end of the program.

arguments:
x - the entire vector x. If this doesn't exist on one processor because of your data layout, then you have to assemble it on one processor.
k - k
elapsedTime - The difference in time as given by MPI_Wtime() (on processor 0) between the start of CG calculation and the end.
*/
int cs240_verify(double* x, int k, double elapsedTime);

#endif