Start Task 2

2025.04.18/02Ex/Makefile

@@ -0,0 +1,42 @@
+WFLAGS = -fstack-protector-all -W -Wall -Wextra -Wunused \
+-Wempty-body -Wlogical-op -Wold-style-declaration -Wmissing-parameter-type \
+-Wignored-qualifiers -Winit-self -Wshadow -Wtype-limits \
+-Wpointer-arith -Wformat-security -Wmissing-format-attribute -Wformat=1 \
+-Wdeclaration-after-statement -Wbad-function-cast -Wnested-externs \
+-Wmissing-prototypes -Wmissing-declarations -Wold-style-definition \
+-Wcast-align -Werror -pedantic -pedantic-errors -Wfloat-equal \
+-Wwrite-strings -Wno-long-long -std=gnu99 -Wstrict-prototypes \
+-Wmissing-field-initializers -Wpointer-sign
+
+CFLAGS = -std=gnu99 -mfpmath=sse -O3
+
+ifeq ($(OS),Windows_NT)
+	EXE = exe
+	CLEAN = del
+	LFLAGS = -lssp -lm
+else
+	EXE = out
+	CLEAN = rm -f
+	LFLAGS = -lm
+endif
+
+TARGET = a02.$(EXE)
+OBJ = main.o solve.o array_io.o
+
+%.o: %.c
+	gcc $(CFLAGS) $(WFLAGS) -c $< -o $@
+
+$(TARGET): $(OBJ)
+	gcc $^ -o $@ $(LFLAGS)
+
+# Отладочная сборка (gdb)
+gdb: CFLAGS = -mfpmath=sse -std=gnu99 -g -O0
+gdb: clean $(TARGET)
+
+# Профилировочная сборка (gprof)
+prof: CFLAGS = -std=gnu99 -mfpmath=sse -pg -O3
+prof: LFLAGS = -lm -pg
+prof: clean $(TARGET)
+
+clean:
+	$(CLEAN) *.o *$(EXE)

2025.04.18/02Ex/array_io.c

@@ -0,0 +1,26 @@
+#include <stdio.h>
+#include <string.h>
+#include "array_io.h"
+
+io_status read_values (double * restrict X, double * restrict Y, const int n, const char * restrict name)
+{
+	FILE *fp;
+	if (!(fp = fopen(name, "r"))) 
+		return ERROR_OPEN;
+
+	for (int i = 0; i < n; ++i)
+		if (fscanf(fp, "%lf\t%lf", X + i, Y + i) != 2)
+		{ fclose(fp); return ERROR_READ; }
+
+	fclose(fp);
+	return SUCCESS;
+}
+
+void print_values (const double * restrict X, const double * restrict Y, const int n, const int p)
+{
+	int np = (n > p ? p : n);
+
+	for (int i = 0; i < np; i++)
+		printf("f(%lf) = %lf\n", X[i], Y[i]);
+}
+

2025.04.18/02Ex/array_io.h

@@ -0,0 +1,9 @@
+#ifndef ARRAY_IO_H
+#define ARRAY_IO_H
+
+#include "io_status.h"
+
+io_status read_values (double * restrict X, double * restrict Y, const int n, const char * restrict name);
+void print_values (const double * restrict X, const double * restrict Y, const int n, const int p);
+
+#endif

2025.04.18/02Ex/io_status.h

@@ -0,0 +1,15 @@
+#ifndef IO_STATUS_H
+#define IO_STATUS_H
+
+#define ERR_MEM	"Error: Not enough memory!"
+#define ERR_OPEN "Error: Cannot open file"
+#define ERR_READ "Error: Cannot read file"
+
+typedef enum _io_status
+{
+	SUCCESS,
+	ERROR_OPEN,
+	ERROR_READ
+} io_status;
+
+#endif

2025.04.18/02Ex/main.c

@@ -0,0 +1,73 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+
+#include "array_io.h"
+#include "io_status.h"
+#include "solve.h"
+
+/* ./a.out x_0 n filename */
+int main(int argc, char *argv[])
+{
+	double x_0, t, r = 0, *X = 0, *Y = 0;
+	int n, task = 2;
+	char *name = 0;
+	io_status ret;
+
+	if (
+			!((argc == 4) && 
+			sscanf(argv[1], "%lf", &x_0) == 1 &&
+			((sscanf(argv[2], "%d", &n) == 1) && n > 0) &&
+			((name = argv[3]) && name))
+	) {
+		fprintf(stderr, "Usage: %s x_0 n filename\n", argv[0]);
+		return 1;
+	}
+
+	X = (double *)malloc(n * sizeof(double));
+	if (!X)
+	{
+		fprintf(stderr, "%s\n", ERR_MEM);
+		return 2;
+	}
+	
+	Y = (double *)malloc(n * sizeof(double));
+	if (!Y)
+	{
+		free(X);
+		fprintf(stderr, "%s\n", ERR_MEM);
+		return 2;
+	}
+
+	ret = read_values(X, Y, n, name);
+	do {
+		switch (ret)
+		{
+			case SUCCESS:
+				continue;
+			case ERROR_OPEN:	
+				fprintf(stderr, "%s '%s'!\n", ERR_OPEN, name);
+				break;
+			case ERROR_READ:
+				fprintf(stderr, "%s '%s'!\n", ERR_READ, name);
+				break;
+		}
+
+		free(X);
+		free(Y);
+
+		return 3; 
+	} while (0);
+
+	t = clock();
+	r = t2_solve(x_0, n, X, Y);
+	t = (clock() - t) / CLOCKS_PER_SEC;
+	
+	printf("%s : Task = %d Result = %e Elapsed = %.2f\n", argv[0], task, r, t);
+
+	free(X);
+	free(Y);
+
+	return 0;
+}
+

2025.04.18/02Ex/solve.c

@@ -0,0 +1,56 @@
+#include "solve.h"
+
+#include <float.h>
+#include <math.h>
+#include <stdio.h>
+
+// the Newton interpolation polynomial
+double t2_solve (const double x_0, const int n, const double * restrict X, double * restrict Y)
+{
+	double last_x = X[n-1];
+	double last_y = Y[n-1];
+	
+	double value = 0;
+	double start_value = 0;
+
+	for (int k = 0; k < n-1; ++k)
+	{
+		printf ("------- K = %d -------\n", k);
+
+		for (int i = n-2; i >= k; --i)
+		{
+			const double x_i = X[i-k];
+			const double y_i = Y[i];
+			
+			if (fabs(last_x - x_i) < DBL_EPSILON)
+				return DBL_MAX;
+			
+//			printf ("Y[%d] = (%lf - %lf) / (%lf - %lf)\n", i+1, last_y, y_i, last_x, x_i);
+			Y[i+1] = (last_y - y_i) / (last_x - x_i);
+			printf ("I = %d, f(x%d, ... , x%d) = %lf\n", i, i-k+1, i+2, Y[i]);
+
+			last_x = x_i;
+			last_y = y_i;
+		}
+
+		last_x = X[n-1];
+		last_y = Y[n-1];
+	}
+
+	last_x = X[0];
+	start_value = 1;
+	value = Y[0];
+
+	for (int i = 1; i < n; ++i)
+	{
+		start_value *= (x_0 - last_x);
+		if (fabs(Y[i]) > DBL_EPSILON) 
+			value += Y[i] * start_value;
+		printf ("i = %d, start_value = %lf, value = %lf, last_x = %lf\n", i, start_value, value, last_x);
+		printf ("Y[%d] = %lf\n", i, Y[i]);
+		last_x = X[i];
+	}
+
+	return value;
+}
+

2025.04.18/02Ex/solve.h

@@ -0,0 +1,6 @@
+#ifndef SOLVE_H
+#define SOLVE_H
+
+double t2_solve (const double x_0, const int n, const double * restrict X, double * restrict Y);
+
+#endif