(hopefully) working MG with RB implemented

Makefile

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+CC= gcc
+RM= rm -vf
+CFLAGS= -Wall -g -std=c99
+OPENMPFLAG= -fopenmp
+LIBS= -lrt -lm
+
+PROGFILES= mg
+
+main: serial_mg.o parallel_mg.o helpers.o main.c
+	$(CC) $(CFLAGS) $(OPENMPFLAG) serial_mg.o parallel_mg.o helpers.o main.c -o mg $(LIBS)
+
+serial_mg.o: serial_mg.c serial_mg.h
+	$(CC) $(CFLAGS) -c serial_mg.c $(LIBS)
+
+parallel_mg.o: parallel_mg.c parallel_mg.h
+	$(CC) $(CFLAGS) $(OPENMPFLAG) -c parallel_mg.c $(LIBS)
+
+helpers.o: helpers.c helpers.h
+	$(CC) $(CFLAGS) $(OPENMPFLAG) -c helpers.c $(LIBS)
+
+clean:
+	$(RM) *.o $(PROGFILES)

helpers.c

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+#include "helpers.h"
+
+int getIndex(int x, int y, int width) { return x*width + y; }

helpers.h

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+#ifndef HELPERS_H
+#define HELPERS_H
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <math.h>
+
+typedef struct{
+  int N;
+  int Lmax;
+  int size[20];
+  double a[20];
+  double alpha;;
+} param_t;
+
+int getIndex(int x, int y, int width);
+
+#endif

main.c

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+/*======================================================================================
+Rich Brower Sat May 28 00:23:17 EDT 2011
+
+C program based on simple FMV code of  S. F. McCormick, Multigrid Methods, Frontiers in Applied! Mathematics,
+vol. 3, SIAM Books, Philadelphia, 1987.The code is intentionally put into a single file with no input parameters
+to keep is concise. Of course a full code may have more traditional C structures!
+
+We solve the 2-d Laplace problem:    A phi = b
+
+ (A phi)((x,y) = [4 phi(x,y) - phi(x+1,y) - phi(x-1,y) - phi(x,y+1)  -phi(x,y+1)]/a^2 + m^2 phi(x,y) = b(x,y)
+
+ Multiply by scale = 1/(4 + a^2 m^2)
+
+     phi  =  (1 - scale*A) phi +  scale*b = phi + res
+          =     scale * (phi(x+1,y) + phi(x-1,y) + phi(x,y+1) + phi(x,y+1))  +  a^2 scale*b(x,y)
+
+where we use rescaled: res =  a^2 scale b - scale* A phi
+
+with scale(lev) = 1/(4 + pow(2,lev)^2 m^2)      or  the lattice spacing is   a(lev) = pow(2,lev)
+
+So the code is really sovling the new matrix iteration:
+
+      phi(x,y) = [(1- scale(lev) * A)phi](x,y) + res(x,y)
+
+               =  scale(lev) * (phi(x+1,y) + phi(x-1,y) + phi(x,y+1) + phi(x,y+1)) + res
+
+At present relex iteration uses Jacobi method.
+======================================================================================*/
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+#include <math.h>
+#include "helpers.h"
+#include "serial_mg.h"
+#include "parallel_mg.h"
+#include <omp.h>
+
+double const_func(int x);
+double sin_func(int x);
+struct timespec diff(struct timespec start, struct timespec end);
+int main(int argc, char **argv)
+{
+//  struct timespec time1, time2, total;
+
+  // NON-PARALLEL
+  printf("Running Non-Parallelized Multigrid\n");
+ // clock_gettime(CLOCK_MONOTONIC, &time1);
+ double t1, t2;
+ double duration;
+  t1 = omp_get_wtime();
+  multigrid(7, sin_func);
+  //clock_gettime(CLOCK_MONOTONIC, &time2);
+  t2 = omp_get_wtime();
+  duration = (t2 - t1);
+  printf("  Total time: %f seconds\n", duration);
+
+  // PARALLEL
+  printf("Running Parallelized Multigrid\n");
+ // clock_gettime(CLOCK_MONOTONIC, &time1);
+  t1 = omp_get_wtime();
+  parallel_multigrid(7, sin_func);
+  //clock_gettime(CLOCK_MONOTONIC, &time2);
+  t2 = omp_get_wtime();
+  duration = (t2 - t1);
+  printf("  Total time: %f seconds\n", duration);
+
+  // NON-PARALLEL
+  // printf("Running Serial Multigrid\n");
+  // clock_gettime(CLOCK_MONOTONIC, &time1);
+  // serial_multigrid(7);
+  // clock_gettime(CLOCK_MONOTONIC, &time2);
+  // total = diff(time1, time2);
+  // printf("  Serial Total time: %ld.%ld seconds\n", total.tv_sec, total.tv_nsec);
+
+  return 0;
+}
+
+double const_func(int x) {
+  return 4.0;
+}
+
+double sin_func(int x) {
+  return sin( ( (double)(2.0 * 3.14) /256 ) * x );
+}
+
+/*
+struct timespec diff(struct timespec start, struct timespec end)
+{
+  struct timespec temp;
+  if ((end.tv_nsec-start.tv_nsec)<0) {
+    temp.tv_sec = end.tv_sec-start.tv_sec-1;
+    temp.tv_nsec = 1000000000+end.tv_nsec-start.tv_nsec;
+  } else {
+    temp.tv_sec = end.tv_sec-start.tv_sec;
+    temp.tv_nsec = end.tv_nsec-start.tv_nsec;
+  }
+  return temp;
+}
+*/