Questions 10

1. Where exactly are the files gsl_multimin.h and gsl_multiroots.h located in your box?

   Hint: gsl-config --cflags.

2. Consider a Makefile,

   blahblah : data log ; for f in $^; do echo $$f:; cat $$f; done
   data log : Makefile ; echo $@ > $@
   clean    :          ; $(RM) data log
   

   What (and why) will it do and what (and why) will it build? Why double dollars in the first line?
3. Suppose you run the command make main and it fails with diagnostics

   cc     main.c   -o main
   main.c:1:19: fatal error: gsl_sf.h: No such file or directory
   compilation terminated.
   

   Explain the error and how to correct it.

   Hint: clang returns the following diagnostics,

   clang     main.c   -o main
   main.c:1:9: fatal error: 'gsl_sf.h' file not found
   #include<gsl_sf.h>
           ^
   1 error generated.
   

4. Suppose you run the command make main and it fails with diagnostics

   cc     main.c   -o main
   /tmp/cce2r3LL.o: In function `main':
   main.c:(.text+0x1e): undefined reference to `gsl_sf_gamma'
   collect2: error: ld returned 1 exit status
   

   Explain the error and how to correct it. Who is "ld" that returned exit status 1?
5. Will this definition of f(t) work (and why)?

   #include"stdio.h"
   #include"math.h"
   int main(){
   	double A=3.5, T=3.2, B=1.2;
   	#define f(t) A*exp(-(t)/T)+B
   	for(double t=0;t<=5;t+=1) printf("%g %g\n",t,f(t));
   return 0;
   }
   

6. Will this definition of f(t) work (and why)?

   #include"stdio.h"
   #include"math.h"
   int main(){
   	double A=3.5, T=3.2, B=1.2;
   	double f(double t){return  A*exp(-t/T)+B;}
   	for(double t=0;t<=5;t+=1) printf("%g %g\n",t,f(t));
   return 0;
   }
   

7. Will this definition of f(t) work (and why)?

   #include"stdio.h"
   #include"math.h"
   #define f(t) A*exp(-(t)/T)+B
   int main(){
   	double A=3.5, T=3.2, B=1.2;
   	for(double t=0;t<=5;t+=0.1) printf("%g %g\n",t,f(t));
   return 0;
   }
   

8. Will this definition of f(t) work (and why)?

   #include"stdio.h"
   #include"math.h"
   double f(double t){return  A*exp(-t/T)+B;}
   int main(){
   	double A=3.5, T=3.2, B=1.2;
   	for(double t=0;t<=5;t+=1) printf("%g %g\n",t,f(t));
   return 0;
   }
   

9. Will this call to print_f_of_one work (and why)?

   #include"stdio.h"
   void print_f_of_one( double (*f)(double) ){printf("%g\n",f(1.0));}
   int main(){
   	double f(double x){return x+x;}
   	print_f_of_one(f);
   return 0;
   }
   

10. Will this call to print_f_of_one work (and why)?

    #include"stdio.h"
    void print_f_of_one( double (*f)(double) ){printf("%g\n",f(1.0));}
    int main(){
    	#define f(x) (x)+(x)
    	print_f_of_one(f);
    return 0;
    }
    

11. Explain the difference between

    echo 'gsl-config --libs'
    

    and

    echo `gsl-config --libs`
    

12. Write a C-program that sends its command-line arguments to the standard output (that is, emulates the echo unix utility).