Using Blas and Lapack libraries in Fortan90 on Linux - makefile

Question

I am trying to use the Lapack and Blas libraries in my Fortran90 code on Linux Mint. I believe I have installed both libraries correctly in the following directory: /usr/local/lib
When I compile my code using a makefile I get the error message:
gfortran -m64 -O3 -fdefault-real-8 -fdefault-double-8 -c MainHPC2.f90
gfortran -m64 MainHPC2.o Central2Scheme.o Central5Scheme.o
WriteDataFiles.o -o P1
MainHPC2.o: In function `MAIN__':
MainHPC2.f90:(.text+0x2b0): undefined reference to `dgesv_'
collect2: error: ld returned 1 exit status
makefile:56: recipe for target 'P1' failed
make: *** [P1] Error 1
My Fortran code is simply trying to call a test function:
call dgesv(nn,nrhsl,al,ldal,ipivl,xl,ldbl,infol)
The makefile I am using is the following:
I believe it is not linking to the libraries properly.
FC = gfortran
FFLAGS = -m64 -O3 -fdefault-real-8 -fdefault-double-8
TARGET_ARCH =
LDFLAGS = -m64
BLIBS = -L/usr/local/lib -llapack -lblas
EXE = P1
.SUFFIXES:
.SUFFIXES: .o .f90 .plt
SRC = \
MainHPC2.f90 \
Central2Scheme.f90 \
Central5Scheme.f90 \
WriteDataFiles.f90 \
$(OBJECTS):
OBJ = ${SRC:.f90=.o}
$(EXE): $(OBJ)
$(FC) $(LDFLAGS) $(OBJ) $(LIBS) -o $(EXE)
%.o : %.f90
$(FC) $(FFLAGS) -c $<
# Define dependencies for modules
# $(OBJ): $(MOD)
clean:
rm -f *.mod *~ core
rm -f *.o
Thank you for your help.
Alex

Answer 1

solution 1
In your makefile, The sections that compile and link never add the $(BLIBS) which contains the BLAS and LAPACK libraries into the linking process.
$(EXE): $(OBJ)
$(FC) $(LDFLAGS) $(OBJ) $(LIBS) $(BLIBS) -o $(EXE)
solution 2
or you made a typo and wrote BLIBS instead of LIBS,
LIBS = -L/usr/local/lib -llapack -lblas
note: This should be more a comment than an answer