When I tried to install qwt manually, I got this error. How can I fix it? Thanks ahead. By the way, I also tried to install qwt by using command yum install, but after that I can't find where the qwt was installed.
rpm -ql qwt will tell you what files it installed. Please note that it's customary for RPM-based distributions to have -dev packages, so you're likely looking for the qwt-dev package.