Why not simply read it in as a parameter using:

CALL GETARG(1,ARGV,LEN)

READ(ARGV,*)PARAM

and launch the program multiple times from a batch file?

prog 1

prog 2

prog 3

etc...

To run your Fortran code with different values of a variable using a loop in your Makefile, you can utilize a target that runs the code with each desired value. Here's an example of how you can modify your Makefile:

# Compiler settings

FC = gfortran

FFLAGS = -O2

# List of values for the variable

KE_VALUES = 1 2 3 4 5

# Target to run the code with different values

run: $(foreach ke,$(KE_VALUES),run_$(ke))

run_%:

$(FC) $(FFLAGS) -DKE=$* -o your_executable your_code.f90 ./your_executable

.PHONY: run $(foreach ke,$(KE_VALUES),run_$(ke))

In the above example, the variable KE_VALUES contains the different values you want to assign to the variable KE. Each value corresponds to a separate target (run_1, run_2, etc.), and the run target is defined to depend on all of these targets.

The run_% target compiles your Fortran code with the specific value of KE defined by the % placeholder. It uses the -D flag to define a preprocessor macro (KE) with the corresponding value, compiles the code, and then executes the resulting executable. You will need to replace your_executable and your_code.f90 with the appropriate names for your code and executable file.

To run the code with all the values of KE, you can simply execute make run in your terminal. Each value of KE will be used in turn to compile and run the code.

Make sure to adjust the compiler settings (FC and FFLAGS) according to your Fortran compiler.