Error in makefile: multiple definition of _start

I have tried to write a makefile: ``` CC = g++ LD = ld CFLAGS = -Wall -std=c++0x -O3 LDFLAGS = -lgsl -lgslcblas -lpthread SOURCES = main.cpp OBJECTS = $(SOURCES:.cpp=.o) EXECUTABLES = main all: $(SOURCES) $(EXECUTABLES) $(EXECUTABLES): $(OBJECTS) $(CC) $(OBJECTS) -o $@ $^ $(LDFLAGS) .cpp.o: $(CC) $(CFLAGS) $< -o $@ .PHONY: clean clean: rm -f *~ *.o main ``` But when I am executing this code, I get the following errors: ``` g++ -Wall -std=c++0x -O3 main.cpp -o main.o main.cpp: In function ‘int main()’: main.cpp:63:12: warning: unused variable ‘order’ [-Wunused-variable] main.cpp:64:12: warning: variable ‘x’ set but not used [-Wunused-but-set-variable] g++ main.o -o main main.o -lgsl -lgslcblas -lpthread main.o: In function `_start': (.text+0x108): multiple definition of `_start' /usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 0 has invalid symbol index 10 /usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 1 has invalid symbol index 11 /usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 2 has invalid symbol index 2 /usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 3 has invalid symbol index 2 /usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 4 has invalid symbol index 10 /usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 5 has invalid symbol index 12 /usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 6 has invalid symbol index 12 /usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 7 has invalid symbol index 12 /usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 8 has invalid symbol index 2 /usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 9 has invalid symbol index 2 /usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 10 has invalid symbol index 11 /usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 11 has invalid symbol index 12 /usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 12 has invalid symbol index 12 /usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 13 has invalid symbol index 12 /usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 14 has invalid symbol index 12 /usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 15 has invalid symbol index 12 /usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 16 has invalid symbol index 12 /usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 17 has invalid symbol index 12 /usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 18 has invalid symbol index 12 /usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 19 has invalid symbol index 12 /usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 20 has invalid symbol index 19 /usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_line): relocation 0 has invalid symbol index 2 /usr/lib/gcc/x86_64-linux-gnu/4.6/../../../x86_64-linux-gnu/crt1.o:/build/buildd/eglibc-2.15/csu/../sysdeps/x86_64/elf/start.S:109: first defined here main.o: In function `_fini': (.fini+0x0): multiple definition of `_fini' /usr/lib/gcc/x86_64-linux-gnu/4.6/../../../x86_64-linux-gnu/crti.o:(.fini+0x0): first defined here main.o:(.rodata+0x0): multiple definition of `_IO_stdin_used' /usr/lib/gcc/x86_64-linux-gnu/4.6/../../../x86_64-linux-gnu/crt1.o:(.rodata.cst4+0x0): first defined here main.o: In function `__data_start': (.data+0x0): multiple definition of `__data_start' /usr/lib/gcc/x86_64-linux-gnu/4.6/../../../x86_64-linux-gnu/crt1.o:(.data+0x0): first defined here main.o: In function `__data_start': (.data+0x8): multiple definition of `__dso_handle' /usr/lib/gcc/x86_64-linux-gnu/4.6/crtbegin.o:(.data+0x0): first defined here main.o: In function `_init': (.init+0x0): multiple definition of `_init' /usr/lib/gcc/x86_64-linux-gnu/4.6/../../../x86_64-linux-gnu/crti.o:(.init+0x0): first defined here main.o: In function `__libc_csu_fini': (.text+0x7f0): multiple definition of `__libc_csu_fini' main.o:(.text+0x7f0): first defined here main.o: In function `_start': (.text+0x108): multiple definition of `_start' /usr/lib/gcc/x86_64-linux-gnu/4.6/../../../x86_64-linux-gnu/crt1.o:/build/buildd/eglibc-2.15/csu/../sysdeps/x86_64/elf/start.S:109: first defined here main.o: In function `Lagrange_coefficient(int, double, int, int)': (.text+0x1f0): multiple definition of `Lagrange_coefficient(int, double, int, int)' main.o:(.text+0x1f0): first defined here main.o: In function `__data_start': (.data+0x80): multiple definition of `datax' main.o:(.data+0x80): first defined here main.o: In function `_fini': (.fini+0x0): multiple definition of `_fini' /usr/lib/gcc/x86_64-linux-gnu/4.6/../../../x86_64-linux-gnu/crti.o:(.fini+0x0): first defined here main.o:(.rodata+0x0): multiple definition of `_IO_stdin_used' /usr/lib/gcc/x86_64-linux-gnu/4.6/../../../x86_64-linux-gnu/crt1.o:(.rodata.cst4+0x0): first defined here main.o: In function `__data_start': (.data+0x0): multiple definition of `__data_start' /usr/lib/gcc/x86_64-linux-gnu/4.6/../../../x86_64-linux-gnu/crt1.o:(.data+0x0): first defined here main.o: In function `Lagrange(double, double)': (.text+0x3b0): multiple definition of `Lagrange(double, double)' main.o:(.text+0x3b0): first defined here main.o:(.bss+0x0): multiple definition of `std::cout@@GLIBCXX_3.4' main.o:(.bss+0x0): first defined here main.o: In function `__data_start': (.data+0x8): multiple definition of `__dso_handle' /usr/lib/gcc/x86_64-linux-gnu/4.6/crtbegin.o:(.data+0x0): first defined here main.o:(.dtors+0x8): multiple definition of `__DTOR_END__' main.o:(.dtors+0x8): first defined here main.o: In function `__libc_csu_init': (.text+0x760): multiple definition of `__libc_csu_init' main.o:(.text+0x760): first defined here main.o: In function `__data_start': (.data+0x20): multiple definition of `datay' main.o:(.data+0x20): first defined here main.o: In function `main': (.text+0x0): multiple definition of `main' main.o:(.text+0x0): first defined here main.o: In function `_init': (.init+0x0): multiple definition of `_init' /usr/lib/gcc/x86_64-linux-gnu/4.6/../../../x86_64-linux-gnu/crti.o:(.init+0x0): first defined here /usr/lib/gcc/x86_64-linux-gnu/4.6/crtend.o:(.dtors+0x0): multiple definition of `__DTOR_END__' main.o:(.dtors+0x8): first defined here /usr/bin/ld: error in main.o(.eh_frame); no .eh_frame_hdr table will be created. /usr/bin/ld: error in main.o(.eh_frame); no .eh_frame_hdr table will be created. collect2: ld returned 1 exit status make: *** [main] Error 1 ``` So, what am I doing wrong, and how can I fix it? If requested I can add my code, too. (But the code works when I am compiling it with `g++ -Wall -O3 -std=c++0x $1 -lgsl -lgslcblas`. Thank you!