Linking GSL to C via make

Question

Umpteenth linking question. I am trying to build some simple C code that calls the GNU scientific library. However, the GSL folder is not nested in my project folder. So, the code lives in, say, C:/c-examples/ and the GSL library is C:/gsl.

This is the C code

#include <stdio.h>
#include <gsl_math.h>
#include <fit/gsl_fit.h>

     int
     main (void)
     {
       int i, n = 4;
       double x[4] = { 1970, 1980, 1990, 2000 };
       double y[4] = {   12,   11,   14,   13 };
       double w[4] = {  0.1,  0.2,  0.3,  0.4 };

       double c0, c1, cov00, cov01, cov11, chisq;

       gsl_fit_wlinear (x, 1, w, 1, y, 1, n,
                        &c0, &c1, &cov00, &cov01, &cov11,
                        &chisq);

       printf ("# best fit: Y = %g + %g X\n", c0, c1);
       printf ("# covariance matrix:\n");
       printf ("# [ %g, %g\n#   %g, %g]\n",
               cov00, cov01, cov01, cov11);
       printf ("# chisq = %g\n", chisq);

       for (i = 0; i < n; i++)
         printf ("data: %g %g %g\n",
                        x[i], y[i], 1/sqrt(w[i]));

       printf ("\n");

       for (i = -30; i < 130; i++)
         {
           double xf = x[0] + (i/100.0) * (x[n-1] - x[0]);
           double yf, yf_err;

           gsl_fit_linear_est (xf,
                               c0, c1,
                               cov00, cov01, cov11,
                               &yf, &yf_err);

           printf ("fit: %g %g\n", xf, yf);
           printf ("hi : %g %g\n", xf, yf + yf_err);
           printf ("lo : %g %g\n", xf, yf - yf_err);
         }
       return 
}

And here is the makefile I wrote for it:

CC=gcc
CFLAGS=-Wall -IC:/gsl -lgsl
OLSexample: OLSexample.o 

clean:
    rm -f OLSexample OLSexample.o

However, running make on this exits with error 2, file not found. I think I might be doing something wrong in the makefile specifying the dependencies, or in linking the libraries. Any help is welcome.

---

EDIT2:

Following mux's advice, and the template here I changed the makefile to the following (including the full paths to the library). I continue to get the previous error (e=2).

CC=gcc
CFLAGS=-c -Wall -IE:/programming/c/libraries/gsl-1.15.tar/gsl-1.15/
LDFLAGS= -LE:/programming/c/libraries/gsl-1.15.tar/gsl-1.15/
LIBS= -lgsl
SOURCES=OLSexample.c
OBJECTS=$(SOURCES:.c=.o)
EXECUTABLE=OLSexample

all: $(SOURCES) $(EXECUTABLE)

$(EXECUTABLE): $(OBJECTS)
    $(CC) $(LDFLAGS) $(OBJECTS) $(LIBS) -o $@

.c.o:
    $(CC) $(CFLAGS) $< -o $@

The complete error message is included here for reference:

e:\programming\c\WorkingFolder\gslExamples\1-ols>make
make
gcc -c -Wall -IE:/programming/c/libraries/gsl-1.15.tar/gsl-1.15/   -c -o OLSexample.o OLSexample.c
process_begin: CreateProcess((null), gcc -c -Wall -IE:/programming/c/libraries/gsl-1.15.tar/gsl-1.15/ -c -o OLSexample.o OLSexample.c, ...) failed.
make (e=2): The system cannot find the file specified.
make: *** [OLSexample.o] Error 2

Answer 1

You should add -LC:/gsl to the list of searched directories , -I adds an include directory to be searched for headers, and -L adds a directory to be searched for libraries with -l<lib>. However, I don't see you actually compiling anything, maybe you should start with a Makefile template instead:

CC=gcc
CFLAGS=-c -Wall -Ic:/gsl
LDFLAGS= -Lc:/gsl
LIBS= -lgsl
SOURCES=main.c
OBJECTS=$(SOURCES:.c=.o)
EXECUTABLE=hello

all: $(SOURCES) $(EXECUTABLE)

$(EXECUTABLE): $(OBJECTS)
    $(CC) $(LDFLAGS) $(OBJECTS) $(LIBS) -o $@

.c.o:
    $(CC) $(CFLAGS) $< -o $@