HDF-EOS: compilation/linking error c/c++ - c

Question

I am trying to compile an example program to use HDF-EOS. The example code is taken from the HDF-EOS website (I will therefore only post the top section):
/* This example shows how to read a data field in HDF-EOS2 grid data. */
#include <mfhdf.h>
#include <hdf.h>
#include <HdfEosDef.h>
#include <stdio.h>
#include <stdlib.h>
int main(int argc, char **argv)
{
int32 gridfile1;
int32 grid1;
int32 datafield1rank;
int32 datafield1dimsize[32];
int32 datafield1type;
char datafield1dimname[512];
float32 *datafield1data;
int32 i, j;
/* Open 'AMSR_E_L3_RainGrid_B05_200707.hdf' using grid API */
if ((gridfile1 = GDopen("AMSR_E_L3_RainGrid_B05_200707.hdf", DFACC_RDONLY)) == -1) {
fprintf(stderr, "error: cannot open grid 'AMSR_E_L3_RainGrid_B05_200707.hdf'\n");
return -1;
}
return 0;
The corresponding make file looks like this:
HDF4_DIR=<hdf4_path>
HDFEOS2_DIR=<hdfeos2_path>
CC=$(HDF4_DIR)/bin/h4cc
CFLAGS=-I$(HDFEOS2_DIR)/include
LDFLAGS=-L$(HDFEOS2_DIR)/lib
LIBS=-lhdfeos -lGctp
read_grid: read_grid.c
$(CC) $(CFLAGS) $(LDFLAGS) $< $(LIBS) -o $#
In addition to the above mentioned paths I have also added links to the hdf5 library, so my make file looks like this:
HDF4_DIR=<hdf4_path>
HDFEOS2_DIR=<hdfeos2_path>
HDF5_DIR=<hdf5_path>
CC=$(HDF4_DIR)/bin/h4cc
CFLAGS=-I$(HDFEOS2_DIR)/include -I$(HDF4_DIR)/include -I$(HDF5_DIR)/include
LDFLAGS=-L$(HDFEOS2_DIR)/lib64 -L$(HDF4_DIR)/lib64 -L$(HDF5_DIR)/lib64
LIBS=-lhdfeos -lGctp
read_grid: read_grid.c
$(CC) read_hdf_eos.c $(CFLAGS) $(LDFLAGS) $(LIBS) -o $#
The problem now is that it does not compile, throwing linking errors such like this:
<hdfeos2_path>/lib64/libhdfeos.a(GDapi.o): In function `lamazDxDtheta':
<hdfeos2_path>/src/GDapi.c:9579: undefined reference to `sin'
<hdfeos2_path>/src/GDapi.c:9580: undefined reference to `sin'
...
collect2: error: ld returned 1 exit status
So for me this looks like a linking problem, however I have no idea why.
To add to the confusion I get another error:
read_grid.o: In function `main':
read_grid.c:(.text.startup+0x0): multiple definition of `main'
read_grid.o:read_grid.c:(.text.startup+0x0): first defined here
Of course I have not defined main more than once. In a second example program that throws the same linking errors I do not get this error.
So if some one would have an idea on the first problem, the linking, I would be very happy.
SOLUTION:
add -lm at the end of the compile statement in the, removes the linking problem
remove the read_hdf_eos.c in the compile statement, that caused the multiple main issue
Thanks for the comments and hints.