ModSim ass4 taddeus: Started work on vibstring MPI integration, source code cleanup.

modsim/ass4_taddeus/ring/Makefile

 CC=mpicc
-CFLAGS=-Wall -Wextra -pedantic -std=c99 -O0 -lm
+CFLAGS=-Wall -Wextra -pedantic -std=c99 -O0
+LDFLAGS=-lm
 
 all: test ring
 test: ring_test.o

modsim/ass4_taddeus/ring/report/report.tex

@@ -8,7 +8,8 @@
 \setlength{\parskip}{1ex plus 0.5ex minus 0.2ex}
 
 \title{Modelleren, Simuleren \& Contin\"ue Wiskunde \\
-       Opdracht 4: Parallel programming - Ringcommunicatie}
+       Opdracht 4: Parallel programming \\
+       Deel 1: Ringcommunicatie}
 \author{Tadde\"us Kroes (6054129)}
 
 \begin{document}

modsim/ass4_taddeus/vibstring/.gitignore

 seq
-seq2
+par

modsim/ass4_taddeus/vibstring/Makefile

-CC=gcc
+CC=mpicc
 CFLAGS=-Wall -Wextra -pedantic -std=c99 -O0 -D_GNU_SOURCE
 LDFLAGS=-lm
 
-all: seq
+all: seq par
 seq: seq.o
+par: par.o
 
 clean:
-	rm -vf *.o vibstring
+	rm -vf *.o seq par

modsim/ass4_taddeus/vibstring/par.c

+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <math.h>
+#include <mpi.h>
+
+double **y = NULL, dx;
+int steps, time, start, rank, tasks;
+
+static inline int first_node() {
+    return !rank;
+}
+
+static inline int last_node() {
+    return rank == tasks - 1;
+}
+
+/*
+ * Connect the string at both ends by sending the calculated border values and
+ * receiving the outer borders calculated by the adjacent nodes
+ */
+void connect(int state) {
+    double send[2], recv[2];
+    int source = (rank - 1 + tasks) % tasks, target = (rank + 1) % tasks;
+    MPI_Status status;
+
+    send[0] = y[state][1];
+    send[1] = y[state][steps];
+
+    MPI_Sendrecv(send, 2, MPI_DOUBLE, target, MPI_ANY_TAG, recv, 2, MPI_DOUBLE,
+            source, MPI_ANY_TAG, MPI_COMM_WORLD, &status);
+
+    y[state][0] = recv[0];
+    y[state][steps + 1] = recv[1];
+}
+
+static inline void init_borders() {
+    // The string is attached at both ends
+    if( first_node() )
+        y[2][1] = y[1][1] = y[0][1];
+    else if( last_node() )
+        y[2][steps] = y[1][steps] = y[0][steps];
+
+    connect(0);
+}
+
+/*
+ * Fill the assigned string section with a sinus shape
+ */
+void init_sinus(double l, double n) {
+    for( int i = 0; i < steps; i++ )
+        y[0][i + 1] = sin(n * M_PI * (i + start) * dx / l);
+
+    init_borders();
+}
+
+/*
+ * Fill the assigned string section with a plucked shape
+ */
+void init_plucked(double l, double xp) {
+    double x;
+
+    for( int i = 0; i < steps; i++ ) {
+        x = (i + start) * dx;
+        y[0][i + 1] = x < xp ? x / xp : (l - x) / (l - xp);
+    }
+
+    init_borders();
+}
+
+#define VERBOSE
+
+#ifdef VERBOSE
+#define PRINT_FORMAT "%e"
+
+void print(int index) {
+    for( int i = 0; i < steps; i++ ) {
+        if( i )
+            printf(" ");
+
+        printf(PRINT_FORMAT, y[index][i]);
+    }
+
+    puts("");
+}
+#endif
+
+/*
+ *
+ */
+void calculate_steps(int time, double tau) {
+    double x;
+    int i, t, prev = 0, current = 1, next = 2;
+
+    // Calculate the position over the entire string at time dt using the
+    // position at t = 0 and the information that y(x, -dt) == y(x, dt)
+    for( i = 1; i < steps - 1; i++ ) {
+        x = i * dx;
+        y[1][i] = y[0][i] + .5 * tau * tau * (y[0][i-1] - 2 * y[0][i]
+                  + y[0][i+1]);
+    }
+
+    #ifdef VERBOSE
+    // Print x values (which are the same for every y-series)
+    for( i = 0; i < steps; i++ ) {
+        if( i )
+            printf(" ");
+
+        printf(PRINT_FORMAT, i * dx);
+    }
+
+    puts("");
+
+    // Print init states
+    print(prev);
+    print(current);
+    #endif
+
+    // Iterate over the length of the string for each time interval step
+    for( t = 2; t < time; t++ ) {
+        for( i = 1; i < steps - 1; i++ ) {
+            y[next][i] = 2 * y[current][i] - y[prev][i] + tau * tau
+                * (y[current][i-1] - 2 * y[current][i] + y[current][i+1]);
+        }
+
+        #ifdef VERBOSE
+        print(next);
+        #endif
+
+        prev = current;
+        current = next;
+        next = (next + 1) % 3;
+    }
+}
+
+int main(int argc, char **argv) {
+    int error, time, i, total_steps;
+    void (*init_method)(double, double);
+    double l, tau, constant;
+
+    // Initialize and setup MPI
+    if( (error = MPI_Init(&argc, &argv)) != MPI_SUCCESS ) {
+        printf("MPI_init failed (error %d)\n", error);
+        MPI_Abort(MPI_COMM_WORLD, error);
+        return EXIT_FAILURE;
+    }
+
+    MPI_Comm_size(MPI_COMM_WORLD, &tasks);
+    MPI_Comm_rank(MPI_COMM_WORLD, &rank);
+
+    // Parse arguments
+    if( argc < 7 ) {
+        printf("Usage: %s INIT_METHOD CALCULATION_STEPS LENGTH DX TAU N|XP\n",
+               argv[0]);
+        return EXIT_FAILURE;
+    }
+
+    if( !strcmp(argv[1], "sinus") ) {
+        init_method = init_sinus;
+    } else if( !strcmp(argv[1], "plucked") ) {
+        init_method = init_plucked;
+    } else {
+        printf("Unknown initialization method '%s'.\n", argv[1]);
+        return EXIT_FAILURE;
+    }
+
+    time = atoi(argv[2]);
+    l = atof(argv[3]);
+    dx = atof(argv[4]);
+    tau = atof(argv[5]);
+    constant = atof(argv[6]);
+
+    // Calculate the indices of the string to calculate
+    total_steps = (int)ceil(l / dx);
+    steps = total_steps / tasks;
+    start = steps * rank;
+
+    // Fill in the gap caused by rounding errors in the last node. Also,
+    // allocate the left and right outer border values that are calculated by
+    // other nodes
+    if( rank == tasks - 1 )
+        steps += total_steps - steps * (tasks - 1);
+
+    // Allocate a 3xN two-dimensional area for this part of the string that
+    // functions as a cyclic buffer for three states of the string (previous,
+    // current, next)
+    y = (double **)malloc(3 * sizeof(double *));
+
+    for( i = 0; i < 3; i++ )
+        y[i] = (double *)malloc((steps + 2) * sizeof(double));
+
+    // Initialize the string values (sinus/plucked)
+    (*init_method)(l, constant);
+
+    // Calculate the specified number of steps
+    calculate_steps(time, tau);
+
+    // Free allocated memory
+    for( i = 0; i < 3; i++ )
+        free(y[i]);
+
+    free(y);
+
+    // Finalize mPI
+    MPI_Finalize();
+
+    return EXIT_SUCCESS;
+}

modsim/ass4_taddeus/vibstring/report/report.tex

@@ -8,7 +8,8 @@
 \setlength{\parskip}{1ex plus 0.5ex minus 0.2ex}
 
 \title{Modelleren, Simuleren \& Contin\"ue Wiskunde \\
-       Opdracht 4: Parallel programming - Trillende snaar}
+       Opdracht 4: Parallel programming \\
+       Deel 2: Trillende snaar}
 \author{Tadde\"us Kroes (6054129)}
 
 \begin{document}

modsim/ass4_taddeus/vibstring/seq.c

@@ -4,18 +4,18 @@
 #include <math.h>
 
 double **y = NULL, dx;
-int x_steps, calc_steps, print_resolution;
+int steps, time;
 
 /*
  *
  */
 void init_sinus(double l, double n) {
-    for( int i = 0; i < x_steps; i++ )
+    for( int i = 0; i < steps; i++ )
         y[0][i] = sin(n * M_PI * i * dx / l);
 
     // The string is attached at both ends
     y[2][0] = y[1][0] = y[0][0];
-    y[2][x_steps - 1] = y[1][x_steps - 1] = y[0][x_steps - 1];
+    y[2][steps - 1] = y[1][steps - 1] = y[0][steps - 1];
 }
 
 /*
@@ -24,14 +24,14 @@ void init_sinus(double l, double n) {
 void init_plucked(double l, double xp) {
     double x;
 
-    for( int i = 0; i < x_steps; i++ ) {
+    for( int i = 0; i < steps; i++ ) {
         x = i * dx;
         y[0][i] = x < xp ? x / xp : (l - x) / (l - xp);
     }
 
     // The string is attached at both ends
     y[2][0] = y[1][0] = y[0][0];
-    y[2][x_steps - 1] = y[1][x_steps - 1] = y[0][x_steps - 1];
+    y[2][steps - 1] = y[1][steps - 1] = y[0][steps - 1];
 }
 
 #define VERBOSE
@@ -40,7 +40,7 @@ void init_plucked(double l, double xp) {
 #define PRINT_FORMAT "%e"
 
 void print(int index) {
-    for( int i = 0; i < x_steps; i++ ) {
+    for( int i = 0; i < steps; i++ ) {
         if( i )
             printf(" ");
 
@@ -54,13 +54,13 @@ void print(int index) {
 /*
  *
  */
-void calculate_steps(int calc_steps, double tau) {
+void calculate_steps(int time, double tau) {
     double x;
     int i, t, prev = 0, current = 1, next = 2;
 
     // Calculate the position over the entire string at time dt using the
     // position at t = 0 and the information that y(x, -dt) == y(x, dt)
-    for( i = 1; i < x_steps - 1; i++ ) {
+    for( i = 1; i < steps - 1; i++ ) {
         x = i * dx;
         y[1][i] = y[0][i] + .5 * tau * tau * (y[0][i-1] - 2 * y[0][i]
                   + y[0][i+1]);
@@ -68,7 +68,7 @@ void calculate_steps(int calc_steps, double tau) {
 
     #ifdef VERBOSE
     // Print x values (which are the same for every y-series)
-    for( i = 0; i < x_steps; i++ ) {
+    for( i = 0; i < steps; i++ ) {
         if( i )
             printf(" ");
 
@@ -83,8 +83,8 @@ void calculate_steps(int calc_steps, double tau) {
     #endif
 
     // Iterate over the length of the string for each time interval step
-    for( t = 2; t < calc_steps; t++ ) {
-        for( i = 1; i < x_steps - 1; i++ ) {
+    for( t = 2; t < time; t++ ) {
+        for( i = 1; i < steps - 1; i++ ) {
             y[next][i] = 2 * y[current][i] - y[prev][i] + tau * tau
                 * (y[current][i-1] - 2 * y[current][i] + y[current][i+1]);
         }
@@ -100,11 +100,11 @@ void calculate_steps(int calc_steps, double tau) {
 }
 
 int main(int argc, const char **argv) {
-    int calc_steps, i;
+    int time, i;
     void (*init_method)(double, double);
     double l, tau, constant;
 
-    // Parse argument
+    // Parse arguments
     if( argc < 7 ) {
         printf("Usage: %s INIT_METHOD CALCULATION_STEPS LENGTH DX TAU N|XP\n",
                argv[0]);
@@ -120,7 +120,7 @@ int main(int argc, const char **argv) {
         return EXIT_FAILURE;
     }
 
-    calc_steps = atoi(argv[2]);
+    time = atoi(argv[2]);
     l = atof(argv[3]);
     dx = atof(argv[4]);
     tau = atof(argv[5]);
@@ -128,7 +128,7 @@ int main(int argc, const char **argv) {
 
     // Allocate a 3xN two-dimensional area that functions as a cyclic buffer
     // for three states of the string (previous, current, next)
-    x_steps = (int)ceil(l / dx);
+    steps = (int)ceil(l / dx);
 
     if( (y = (double **)malloc(3 * sizeof(double *))) == NULL ) {
         puts("Error: could not allocate memory.");
@@ -136,13 +136,13 @@ int main(int argc, const char **argv) {
     }
 
     for( i = 0; i < 3; i++ )
-        y[i] = (double *)malloc(x_steps * sizeof(double));
+        y[i] = (double *)malloc(steps * sizeof(double));
 
     // Initialize the string values (sinus/plucked)
     (*init_method)(l, constant);
 
     // Calculate the specified number of steps
-    calculate_steps(calc_steps, tau);
+    calculate_steps(time, tau);
 
     // Free allocated memory
     for( i = 0; i < 3; i++ )