Explanation to an assignment

Question

I am NOT looking for an answer to this problem. I am having trouble understanding what I should be trying to accomplish in this assignment. I welcome Pseudo code or hints if you would like. but what I really need is an explanation to what I need to be making, and what the output should be/look like. please do not write out a lot of code though I would like to try that on my own.

(()) = notes from me

The assignment is:

a program (prog.exe) ((we are given this program)) that reads 2 integers (m, n) and 1 double (a) from an input data file named input.in. For example, the sample input.in given file contains the values

5 7 1.23456789012345

when you run ./prog.exe the output is a long column of floating-point numbers

in additions to the program, there is a file called ain.in that contains a long column of double precision values.

copy prog.exe and ain.in to working directory

Write a bash script that does that following:

-Runs ./prog.exe for all combonations of

--m=0,1,...,10

--n=0,1,...,5

--a=every value in the file ain.in

-this is essentially a triple nested loop over m,n and the ain.in values

-for each combination of m,n and ain.in value above:

-- generate the appropriate input file input.in

-- run the program and redirect the output to some temporary output file.

--extract the 37th and 51st values from this temporary output file and store these in a file called average.in

-when the 3 nested loops terminate the average.in file should contain a long list of floating point values.

-your script should return the average of the values contained in average.in

HINTS: seq , awk , output direction, will be useful here

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thank you to whoever took the time to even read through this. This is my second bash coding assignment and im still trying to get a grasp on it and a better explanation would be very helpful. thanks again!

Answer 1

this is one way of generating all input combinations without explicit loops

join -j9 <(join -j9 <(seq 0 10) <(seq 0 5)) ain.in | cut -d' ' -f2-

Answer 2

The idea is to write a bash script that will test prog.exe with a variety of input conditions. This means recreating input.in and running prog.exe many times. Each time you run prog.exe, input.in should contain a different three numbers, e.g.,

First run:

0 0 <first line of ain.in>

Second run:

0 0 <second line of ain.in>

. . . last run:

10 5 <last line of ain.in>

You can use seq and for loops to accomplish this.

Then, you need to systematically save the output of each run, e.g.,

./prog.exe > tmp.out
# extract line 37 and 51 and append to average.ln
sed -n '37p; 51p; 51q' tmp.out >> average.ln

Finally, after testing all the combinations, use awk to compute the average of all the lines in average.in.

Answer 3

One-liner inspired by @karakfa:

join -j9 <(join -j9 <(seq 0 10) <(seq 0 5)) ain.in | cut -d' ' -f2- |
    sed "s/.*/echo & >input.in;./prog.exe>tmp.out; sed -n '37p;51p;51q' tmp.out/" |
    sh | awk '{sum+=$1; n++} END {print sum/n}'