Graphical interface for the previous command based program was implemented with the help of GTK3 library. Install GTK3 library and then compile the program Curve_fit.c as follows, As explained for command based program, the graphical based progrm also require two input files namely, Data and Limit. By clicking the "Data" / "Limit" button on the left pane editable notebook tab will be opened where the input files can be prepared by either typing or copying the entry from an excel sheet. After the entry, the files are saved under the name "Data" and Limit" in the same folder where the program executable is present aswellas run.export PKG_CONFIG_PATH='/home/Software/GTK3/Library/GTK3/lib/pkgconfig' gcc -o Curve_fit Curve_fit.c `pkg-config --cflags --libs gtk+-3.0` -lm -lgsl -lgslcblas or explicitly gcc -o Curve_fit Curve_fit.c -lpthread -I/usr/include -I/home/Software/GTK3/Library/GTK3/include/gtk-3.0 -I/home/Software/GTK3/Library/GTK3/include/atk-1.0 -I/home/Software/GTK3/Library/GTK3/include/at-spi2-atk/2.0 -I/home/Software/GTK3/Library/GTK3/include/pango-1.0 -I/home/Software/GTK3/Library/GTK3/include/gio-unix-2.0/ -I/home/Software/GTK3/Library/GTK3/include/cairo -I/home/Software/GTK3/Library/GTK3/include/gdk-pixbuf-2.0 -I/home/Software/GTK3/Library/GTK3/include/glib-2.0 -I/home/Software/GTK3/Library/GTK3/lib/glib-2.0/include -I/home/Software/GTK3/Library/GTK3/include/at-spi-2.0 -I/home/Software/GTK3/Library/GTK3/include/dbus-1.0 -I/home/Software/GTK3/Library/GTK3/lib/dbus-1.0/include -I/home/Software/GTK3/Library/GTK3/include/harfbuzz -I/home/Software/GTK3/Library/GTK3/include -I/usr/include/freetype2 -I/home/Software/GTK3/Library/GTK3/include/pixman-1 -I/usr/include/libpng12 -L/home/Software/GTK3/Library/GTK3/lib -lgtk-3 -lgdk-3 -latk-1.0 -lgio-2.0 -lpangocairo-1.0 -lgdk_pixbuf-2.0 -lcairo-gobject -lpango-1.0 -lcairo -lgobject-2.0 -lglib-2.0 -lm -lgsl -lgslcblas |