[Help-gsl] gsl example

[Kevin Luxford]

I am using Cygwin64 on a Windows 10 computer.  I have downloaded the gsl 
pack.  The header files are in /usr/local/include.  I have used nano to 
enter the example code from the gsl reference pdf into a file named 
example.c.  I have used the compile and link commands as in the gsl 
reference (by copying from the reference and pasting into my Gygwin64 
terminal).  The only modification is that I use -o example.exe as the 
first argument in the linker command.  I executed example.exe and 
received a value for the Bessel function J0(x) for x = 5 of J0(5) = 
-1.917848549326277019e-01 instead of J0(5) = -1.775967713143382642e-01.

Could anyone please explain to this old newby why he got a different 
solution?
Thanks
Kevin