Questions 6

1. In gnuplot, how do you specify the ranges on the x- and y- axes?

2. In the datafile for gnuplot, how do you separate data intended for separate lines on the plot?

3. Suppose you have a data-file with several columns of data. With gnuplot, how do you plot, say, third column vs. second? Hint: in gnuplot: help plot using.

4. Suppose you have a data-file with (x,y) data organised in two columns. How do you plot, say, y² vs. x? Hint: in gnuplot: help plot using.

5. How can you find out whether GSL is installed on your box? Hint: gsl-config.

6. How can you find out which C-flags you need to use with your GSL installation? Hint: gsl-config.

7. How can you find out which libraries you need to link with your GSL installation? Hint: gsl-config.

8. Explain the syntax `command` and $(command) in bash. Hint: Bash command substitution; POSIX shell command substitution.

9. Why do you need double-dollar, $$(command), in the Makefile? Hint: GNU make: variables in recipes.

10. What is "recipe echoing"?

11. What will the following Makefile print?

    pwd = a string
    test:
    	@echo pwd
    	@echo `pwd`
    	@echo $(pwd)
    	@echo $$(pwd)
    

12. In C-language "type conversion" (or "coersion" or "casting") is allowed with the explicit cast operator (type)variable. So, what does the following line mean?

    double  a = *(double*)params;