undefined references when using fftw3.3.6 with threads and float enabled - c

Question

I installed fftw3.3.6 on my Ubuntu 16.04 to test the performance of using this library with thread and float enabled.
Step 1 :
Installed the library with thread and float and SIMD instructions enabled:`
sudo ./configure --enable-float --enable-generic-simd128 --enable-generic-simd256 --enable-threads
make
make install
Step 2 :
I wrote this code (basing on the manual and tutorial) to compute an fft of 1024 points using 4 threads (complex to complex):
#include <stdio.h>
#include <stdlib.h>
#include <fftw3.h>
#include "input.h"
#define NUMBER_OF_ELEMENTS 1024
#define NUM_THREADS 4
void Load_inputs(fftwf_complex* data)
{
int i;
for(i=0;i<NUMBER_OF_ELEMENTS;i++)
{
data[i][0] = input_data[2 * i];
data[i][1] = input_data[2 * i + 1];
}
}
int main()
{
fftwf_complex array[NUMBER_OF_ELEMENTS];
fftwf_plan p;
int i;
fftwf_init_threads();
fftwf_plan_with_nthreads(NUM_THREADS);
p = fftwf_plan_dft(1,NUMBER_OF_ELEMENTS,array,array,FFTW_FORWARD,FFTW_EXHAUSTIVE);
Load_inputs(array); //function to load input data from input.h file to array[]
fftwf_execute(p);
FILE* res = NULL;
res = fopen("result.txt", "w");
for ( i = 0; i <1024; i++ )
{
fprintf(res,"RE = %f \t IM = %f\n",array[i][0], array[i][1] );
}
fclose(res);
fftwf_destroy_plan(p);
fftwf_cleanup_threads();
}
And then, I compiled this program with this makefile.
CC=gcc
CFLAGS=-g3 -c -Wall -O0 -mavx -mfma -ffast-math
SOURCES=$ test.c
OBJECTS=$(SOURCES:.c=.o)
EXECUTABLE=test
all: $(TASKMAP) $(SOURCES) $(EXECUTABLE)
$(EXECUTABLE): $(OBJECTS)
$(CC) $(OBJECTS) -o $# -L -lfftw3f_threads -lfftw3f
.c.o:
$(CC) $(CFLAGS) $< -lm -o $#
clean:
rm -fr $(OBJECTS) $(EXECUTABLE)
Compilation errors :
After compilation I've got these errors:
gcc test.o -o test -L -lfftw3f_threads -lfftw3f
//usr/local/lib/libfftw3f.a(mapflags.o): In function `fftwf_mapflags':
mapflags.c:(.text+0x346): undefined reference to `__log_finite'
Makefile:13: recipe for target 'test' failed
//usr/local/lib/libfftw3f.a(trig.o): In function `cexpl_sincos':
trig.c:(.text+0x2c1): undefined reference to `sincos'
//usr/local/lib/libfftw3f.a(trig.o): In function `fftwf_mktriggen':
trig.c:(.text+0x50b): undefined reference to `sincos'
trig.c:(.text+0x653): undefined reference to `sincos'
test.o: In function `main':
/home/anouar/workspace/Thread_example//test.c:27: undefined reference to `fftwf_init_threads'
/home/anouar/workspace/Thread_example//test.c:28: undefined reference to `fftwf_plan_with_nthreads'
/home/anouar/workspace/Thread_example//test.c:40: undefined reference to `fftwf_cleanup_threads'
collect2: error: ld returned 1 exit status
make: *** [test] Error 1
Is there something missing, or something wrong that I have did during installation and compilation?

Answer 1

Read the fine manual. From the sincos() man page:
Link with -lm.
Using -lm in the compile phase of your program is useless:
.c.o:
$(CC) $(CFLAGS) $< -lm -o $#
-lm needs to be in the link stage:
$(EXECUTABLE): $(OBJECTS)
$(CC) $(OBJECTS) -o $# -L -lfftw3f_threads -lfftw3f -lm

Answer 2

In my case, the problems with
undefined reference to `__log_finite'
could be solved by compiling without the -ffast-math option.