updated information

README.md

@@ -32,11 +32,11 @@ To build and run this code, you need to have the following software tools instal
 # Default build instructions:
 
 
-`% cd sum_harness_instructional`     # contains the source files and CMakeLists.txt file  
+    cd sum_harness_instructional     # contains the source files and CMakeLists.txt file  
-`% mkdir build`  
+    mkdir build  
-`% cd build`  
+    cd build  
-`% cmake ../`           # cmake generates lots of output   
+    cmake ../           # cmake generates lots of output   
-`% make`                # to build the programs  
+    make                # to build the programs  
 
 
 
@@ -52,17 +52,17 @@ You will need to add code in three places:
 
 # Running the codes
 
-Once the codes are built, you should be able to just run each one from the command line:
+Once the codes are built, you should be able to just run each one from the command line from within your build directory:
 
-`% ./sum_direct`
+    ./sum_direct  
 
 or 
 
-`% ./sum_indirect`
+    ./sum_indirect  
 
 or
 
-`% ./sum_vector`
+    ./sum_vector  
 
 When you run each code, it will iterate through the set of problem sizes predefined inside benchmark.cpp
 
@@ -74,23 +74,60 @@ After [logging in to perlmutter at NERSC,](https://docs.nersc.gov/systems/perlmu
 
 Set up your environment to make use of the CPU nodes by typing in this command:
 
-`% module load cpu`
+    module load cpu
 
 Then follow the build instructions above.
 
 Once you have built the codes, you may request interactive access to a Perlmutter CPU node by using this command:
 
-`% salloc --nodes 1 --qos interactive --time 00:30:00 --constraint cpu --account=m3930`
+    salloc --nodes 1 --qos interactive --time 00:30:00 --constraint cpu --account=m3930
 
-Once you are on an interactive CPU node, run each of the codes using these commands:
+Once you are on an interactive Perlmutter CPU node, run each of the codes using these commands from within your build directory:
 
-`srun ./sum_direct`
+    ./sum_direct
-`srun ./sum_indirect`
+    ./sum_indirect
-`srun ./sum_vector`
+    ./sum_vector
 
 
+# Using the Python scripts for plotting on Perlmutter@NERSC
+
+Included in the code harness are two Python files that will load a 
+csv text file and use matplotlib.pyplot to create a 3-variable chart.
+Please modify these Python files as needed to update the axis labels, 
+plot title, and so forth.
+
+To run Python on Perlmutter, first do a:
+
+    module load python
+
+That command will make available to you a full conda environment that 
+is preloaded with many of the commonly used Python packages. The default
+version of Python as of the time of this writing is 3.11.6.
+Once you've loaded the python module, you can see the set of 
+installed packages using this command:
+
+    conda list
+
+When you run the provided plot\_3vars.py Perlmutter, it will produce some 
+output to the console and will also attempt to display the plot on your
+screen. 
+
+In order for the display to actually appear on your screen you must use
+the -Y argument with ssh when you login, e.g.:
+
+    ssh -Y user@saul-p1.nersc.gov
+
+There are two python scripts in the distro: plot\_3vars.py and
+plot\_3vars\_savefig.py. The difference between them is that the
+plot\_3vars\_savefig.py will in addition to trying to display
+the plot to the screen also save an image file named *myplot.png*.
+
 # Additional build options -- Compiler Optimization Level
 
+As of the time of this writing (Oct 2023), most SFSU students will not need
+the information about different build options unless otherwise
+instructed.
+
 By default, the CMakeLists.txt will do a "Release" build, which means there will be full compiler optimizations.
 
 If need be, there are two methods for modifying the compiler optimization level.