?Linux下編譯出現以下提示可以在編譯的后面加上-lm，例如，arm-none-linux-gnueabi-gcc -o example1 example1.c -lm，意思就是添加數學庫的意思，編譯就能通過了

example1.c:(.text+0x3e8): undefined reference to `cos'
example1.c:(.text+0x42c): undefined reference to `sin'
example1.c:(.text+0x470): undefined reference to `sin'
example1.c:(.text+0x4b4): undefined reference to `cos'

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