Document prompt engineering steps

doc/ai4dev/README.md

@@ -0,0 +1,34 @@
+Set Up
+-----------
+With your present working directory set to `doc/ai4dev`, execute
+```bash
+cd  ../../scripts/
+./create-single-source-file-programs.sh 
+cd ../build/single-file-programs
+```
+
+Vibe Coding
+-----------
+1. Compile and execute `diffusion-app.F90` to ensure that the program
+   terminates normally.  For example, with the `gfortran` compiler,
+   run `gfortran -fcoarray=single -o diffusion-app diffusion-app.F90` 
+   followed by `./diffusion-app`.
+2. Edit `diffusion-app.F90` to remove the lines beginning and ending with 
+   `module procedure laplacian` and `end procedure laplacian`, respectively.
+3. Enter the file `doc/ai4dev/vibe-coding/README.md` as your prompt and
+   attach the edited `diffusion-app.F90` file.
+4. Insert the resulting function into the `subdomain_s` submodule and
+   try compiling and executing again to check the result.
+
+Idiomtic Vibe Coding
+--------------------
+1. Compile and execute `test-suite.F90` to and check that the output 
+   reports that all tests pass.  For example, with the `gfortran` compiler,
+   run `gfortran -fcoarray=single -o test-suite test-suite.F90` followed
+   by `./test-suite`.
+2. Edit `test-suite.F90` to remove the lines beginning and ending with 
+   `module procedure laplacian` and `end procedure laplacian`, respectively.
+3. Enter the file `doc/ai4dev/idiomaic-vibe-coding/README.md` as your prompt 
+   and attach the edited `tgest-sutie.F90` file.
+4. Insert the resulting function into the `subdomain_s` submodule and
+   try compiling and executing again to check the result.

doc/ai4dev/idiomatic-vibe-coding/README.md

@@ -0,0 +1,14 @@
+
+You are a research software engineer who is familiar with Fortran 2018, experienced in parallel and object-oriented programming, and building a software library named "Matcha". All source code that you need is in the attached file. The main program runs a test suite that uses a module subdomain_test_m to report on several correctness checks on the subdomain_m module and subdomain_s submodule.  The subdomain_m module also contains a module function interface body named "laplacian".  Everything in the source code is complete except that there is no defintion for the "laplacian" function. Provide a defintion for the laplacian function definition using the following steps:
+
+1. Write an empty module procecure named "laplacian" into which you will insert executable statements and comments that explain what your code is doing.
+2. Allocate the laplacian_rhs% component to a shape [my_nx, ny, nz]
+3. Use one or more "do concurrent" constructs, each with "default(none)" and any othe required locality specifiers, to compute a 2nd-order central difference approximation to the Laplacian of the "s_" array component of the "laplacian" function's "rhs" dummy argument.
+4. Store the Laplacian approximation in the s_ component of the laplacian_rhs function result.
+5. When an expresssion requires the value rhs%s_(1,:,:) and me==1, instead use halo_x(west,:,:) for the required value.
+5. When an expresssion requires the value rhs%s_(ubound(rhs%s_,1),:,:) and me==num_subdomains, instead use halo_x(east,:,:) for the required value.
+6. Set result component laplacian_rhs%s_ to zero for the subscript values (:, 1,:), (:,ny,:), (:,:, 1), (:,:,nz). 
+7. Also set laplacian_rhs%s_ to zero for the subscript values (1,:,:) if me==1
+8. Also set laplacian_rhs%s_ to zero for the subscript values (my_nx,:,:) if me==num_subdomains.
+
+When "laplacian" function is incorporated into the subdomain_m module, the attached file must compile and report that all tests passing when executed.

scripts/create-single-source-file-programs.sh

@@ -7,6 +7,7 @@
 export assert_dir="../build/dependencies/assert"
 export julienne_dir="../build/dependencies/julienne"
 export matcha_dir=".."
+export test_dir="../test"
 export destination_dir="../build/single-file-programs"
 
 echo ""
@@ -80,3 +81,7 @@ cp "$julienne_dir/include/julienne-assert-macros.h" "$destination_dir"
 
 echo "Concatenating Assert, Julienne, and Matcha src and app into $destination_dir/diffusion-app.F90"
 cat "$destination_dir"/assert.F90 "$destination_dir"/julienne.F90 "$destination_dir"/matcha.F90 "$matcha_dir/app/diffusion.f90" > $destination_dir/diffusion-app.F90
+
+echo "Concatenating Assert, Julienne, and Matcha src and test into $destination_dir/test-suite.F90"
+test_modules=$(find "$test_dir" -name '*_m.?90')
+cat "$destination_dir"/assert.F90 "$destination_dir"/julienne.F90 "$destination_dir"/matcha.F90 $test_modules "$test_dir"/main.F90 > $destination_dir/test-suite.F90

src/matcha/subdomain_s.F90

@@ -142,7 +142,7 @@
 
     if (me==1) laplacian_rhs%s_(1,:,:) = 0. ! low-x boundary
     if (me==num_subdomains) laplacian_rhs%s_(my_nx,:,:) = 0. ! high-x boundary
-  end procedure
+  end procedure laplacian
 
   module procedure multiply
     call_assert(allocated(rhs%s_))