Eigen library for linear algebra / Teensy 3.1 / Help needed

[aguadopd]

Eigen

I haven't looked at this code (yet). But I am saying at least 2 times before, a very similar error about _kill and _getpid turned out to be related to improper vararg usage, which happened to compile on avr-gcc, even though it's things that are absolutely wrong to do with vararg.

I have no idea if that's what's really going on here. I might dig into this soon, if it's still unresolved. But if anyone is trying now, maybe knowing improper vararg usage on other libraries showed the same errors might help? I believe one of them was EtherCard. Here's the commit that fixed the problem.

https://github.com/PaulStoffregen/EtherCard/commit/de7610f8c9b15f834b3aadba62626a82c9be1b45

Hello everyone. First of all, thanks Paul and all the contributors for making the Teensy a great product. I'm also using the EigenArduino Library..after some time I could make it work, when I discovered I should not use stlport-avr, since the Teensy has it owns implementation of the stl.

After reading some more, I want to say that, besides a lot of warnings related to Eigen, I'm also experiencing compilation errors with kill and getpid and write. Using Arduino IDE 1.6.5 + Teensyduino 1.25 or Arduino IDE 1.6.3 + Teensyduino 1.23, in Ubuntu 14.04. I'm using the EigenArduino library, which is using Eigen 3.06. The problem persists if I try using Eigen 3.2.6 and keeping the EigenArduino header, as suggested by kpc in this same post.

Code: (example for complex Eigenvalues from Eigen documentation, commented out the output...)

#include <Eigen30.h>
#include <Eigen/Eigenvalues>

using namespace Eigen;
using namespace std;

void setup() {
  // put your setup code here, to run once:
  
MatrixXcf A = MatrixXcf::Random(4,4);
//cout << "Here is a random 4x4 matrix, A:" << endl << A << endl << endl;
ComplexEigenSolver<MatrixXcf> ces;
ces.compute(A);
//cout << "The eigenvalues of A are:" << endl << ces.eigenvalues() << endl;
//cout << "The matrix of eigenvectors, V, is:" << endl << ces.eigenvectors() << endl << endl;
complex<float> lambda = ces.eigenvalues()[0];
//cout << "Consider the first eigenvalue, lambda = " << lambda << endl;
VectorXcf v = ces.eigenvectors().col(0);
//cout << "If v is the corresponding eigenvector, then lambda * v = " << endl << lambda * v << endl;
//cout << "... and A * v = " << endl << A * v << endl << endl;
//cout << "Finally, V * D * V^(-1) = " << endl
//<< ces.eigenvectors() * ces.eigenvalues().asDiagonal() * ces.eigenvectors().inverse() << endl;

}

void loop() {
  // put your main code here, to run repeatedly:

}

---

Error:

..../arduino-1.6.5-r5/hardware/tools/arm/bin/arm-none-eabi-gcc -O -Wl,--gc-sections,--relax,--defsym=__rtc_localtime=1445790678 -T ..../arduino-1.6.5-r5/hardware/teensy/avr/cores/teensy3/mk20dx256.ld -mthumb -mcpu=cortex-m4 -fsingle-precision-constant -o /tmp/build3882062423633423646.tmp/sketch_oct25a.cpp.elf /tmp/build3882062423633423646.tmp/sketch_oct25a.cpp.o /tmp/build3882062423633423646.tmp/core.a -L/tmp/build3882062423633423646.tmp -larm_cortexM4l_math -lm 
..../arduino-1.6.5-r5/hardware/tools/arm/bin/../lib/gcc/arm-none-eabi/4.8.4/../../../../arm-none-eabi/lib/armv7e-m/libc.a(lib_a-signalr.o): In function `_kill_r':
signalr.c:(.text._kill_r+0xe): undefined reference to `_kill'
..../arduino-1.6.5-r5/hardware/tools/arm/bin/../lib/gcc/arm-none-eabi/4.8.4/../../../../arm-none-eabi/lib/armv7e-m/libc.a(lib_a-signalr.o): In function `_getpid_r':
signalr.c:(.text._getpid_r+0x0): undefined reference to `_getpid'
..../arduino-1.6.5-r5/hardware/tools/arm/bin/../lib/gcc/arm-none-eabi/4.8.4/../../../../arm-none-eabi/lib/armv7e-m/libc.a(lib_a-writer.o): In function `_write_r':
writer.c:(.text._write_r+0x10): undefined reference to `_write'
collect2: error: ld returned 1 exit status

---

Possible solutions:
- As suggested in this post by davidthings, adding a similar dummy function for write:

extern "C"{
  int _getpid(){ return -1;}
  int _kill(int pid, int sig){ return -1; }
  int _write(){return -1;}
}

- As suggested here by kpc, defining a dummy abort function:

void abort() {
        while(1);
}

Hope it helps.

 

[mconsidine]

In the event anyone is curious, I have had the Eigen library running the example code shown earlier in this thread for all versions of the library since 3.2.4 posted here : http://eigen.tuxfamily.org/index.php?title=Main_Page

One wrinkle cropped up with the beta version of the 3.3.1 package. This was overcome by placing an undef statement at the start of the code, thusly :

// Example By: RandomVibe
// Eigen Doc: http://eigen.tuxfamily.org/dox/
// Quick Reference: http://eigen.tuxfamily.org/dox/QuickRefPage.html
#ifdef round
#undef round
#endif

#include <Eigen331b1.h>     // Calls main Eigen matrix class library
#include <Eigen/LU>             // Calls inverse, determinant, LU decomp., etc.
using namespace Eigen;    // Eigen related statement; simplifies syntax for declaration of matrices

Hope this helps someone,
Matt