编译时对"dgesv_"的未定义引用

Question

我有以下makefile:

CC = gcc

ROOTPATH = /home/swagatam
LIB_PATH = $(ROOTPATH)/mylib/libf2c.a \
            $(ROOTPATH)/mylib/blas_LINUX.a \
        $(ROOTPATH)/mylib/lapack_LINUX.a -lm


INC_PATH = -I$(ROOTPATH)/myinclude

swadgesv : swadgesv.o
    $(CC) $(LIB_PATH) swadgesv.o -o swadgesv

swadgesv.o : swadgesv.c
    $(CC) $(INC_PATH) -c swadgesv.c

clean:
    rm -f *.o

swadgesv.c是程序求解AX = B形式的方程式.我需要3个头文件和3个库来链接解决概率.但是当我在终端中运行Makefile时,它显示:

gcc -I/home/swagatam/myinclude -c swadgesv.c
gcc /home/swagatam/mylib/libf2c.a /home/swagatam/mylib/blas_LINUX.a         /home/swagatam/mylib/lapack_LINUX.a -lm swadgesv.o -o swadgesv
swadgesv.o: In function `main':
swadgesv.c:(.text+0x0): multiple definition of `main'
/home/swagatam/mylib/libf2c.a(main.o):(.text.startup+0x0): first defined  here
/home/swagatam/mylib/libf2c.a(main.o): In function `main':
(.text.startup+0xad): undefined reference to `MAIN__'
swadgesv.o: In function `main':
swadgesv.c:(.text+0xc1): undefined reference to `dgesv_'
collect2: ld returned 1 exit status
make: *** [swadgesv] Error 1

即使我在LIB_PATH中更改库的顺序,它也会显示不同的错误.我从我安装的clapack库中调用函数dgsev.

Answer 1

将库放在目标文件之后:

swadgesv: swadgesv.o
    $(CC) swadgesv.o -o swadgesv $(LIB_PATH)

如果首先列出库,则加载器正在查找符号main(),它通常不会在库中找到它,因此它没有理由链接库中的任何符号并有效地忽略它们.当它最终遇到你的目标文件时,它会找到main(),但是找不到main()目标文件后面(不存在的)参数中引用的符号.因此符号保持不确定.链接行上的参数顺序很重要.