The code is effectively disassociated from anything legacy at this point… but it still needs some tidying up. Firstly we could combine the final two if statements into an if-else statement, which is effectively what they are. Therefore this code:
if (dist.le.30) vel = 2.425+0.00175*dist*dist if (dist.gt.30) vel = 0.625+0.12*dist-0.00025*dist*dist
if (dist .le. 30) then vel = 2.425 + 0.00175*dist*dist else vel = 0.625 + 0.12*dist - 0.00025*dist*dist end if
Next all the old-fashioned conditional operators could be changed, i.e from .le. to <=. Finally we could improve readability by adding some spaces to equations, and remove the stop statement.
Here’s the final piece of code:
There is nothing inherently difficult about the process of re-engineering. This is of course a very simple example, and re-engineering a 10,000 line Fortran program *may* be somewhat of a nightmare… but it *is* possible. Most of all, one has to develop a rigorous process to re-engineer a program. You can’t just go and start editing code, especially as a *lot* of code may not be well documented, or have algorithms which seem cryptic. Stand-alone Fortran functions can be somewhat easier, as they can always be called from other languages such as Julia.