Spurious runtime error using g++ under Linux

[Gary Neil Felder <gfelder at leland dot Stanford dot EDU>]

I am running gcc under Linux 6.0 on a Pentium II 450. When I tried
compiling and running a program which I had written on a different system
it gave me a runtime "segmentation fault" error. I reduced the program to
the simplest form which I could that still contained the error, and I now
have it down to about 20 lines of code which to me look completely
harmless, but which consistently reproduce this error. 

Running g++ -v indicates that I have version 2.91.66 of gcc. I'm including
the makefile and source files I used so that you can see exactly what
options I used. To reproduce the error I simply put all of these files in
a directory and type:

make
./sfe

Note that I copied these files to a UNIX system and the problem did not
appear so I suspect it may be specific to Linux. I also copied them to
another Linux machine and the problem did show up again.

Thank you for your help.

Gary Felder
gfelder@stanford.edu

#include "complex.h"

Complex :: Complex(float real, float imag) : real_(real), imag_(imag)
{ }

/*
Complex :: Complex(const Complex& c)
{
  real_ = c.real_;
  imag_ = c.imag_;
}

Complex& Complex :: operator=(const Complex& c) // Assignment operator
{
  real_ = c.real_;
  imag_ = c.imag_;
  return *this;
}
*/
class Complex
{
public:
  Complex(float real = 0, float imag = 0); // Default
  //  Complex(const Complex& c); // Creates a copy of c
  //  Complex& operator=(const Complex& c); // Assignment operator

private:
  float real_;
  float imag_;
};
CC = g++
FLAGS = -O3

all: complex.h complex.o sfe.o
	$(CC) $(FLAGS) complex.o sfe.o -lm -o sfe

clean:
	rm -f *.o sfe

complex.o: complex.cpp complex.h
	$(CC) -c $(FLAGS) complex.cpp

sfe.o: sfe.cpp
	$(CC) -c $(FLAGS) sfe.cpp

#include "complex.h"
#include <math.h>
#include <stdio.h>

float psm;

int main()
{
        Complex af;
	float xmax=10.5;

	printf("generating initial conditions ...\n");
	psm=pow(xmax,1.5);

	return(0);
}