Guide To Learn
Once you have a compiled program executable, it’s not obvious how it was compiled. Specifically, what compiler was used, and were any compiler options used–for example, for debugging or optimization? Fortran’s iso_fortran_env module provides two functions that allow you to get this information at runtime: compiler_version and compiler_options. You get the idea what each of these functions does. Let’s write a program that […]
Before we venture into writing our own custom modules, let’s first get familiar by accessing a built-in module that comes with Fortran out of the box. Fortran has a few built-in modules. The most commonly used one is iso_fortran_env, which, among other things, provides constants and procedures that allow you to write more portable programs. Another commonly […]
functional-fortran: http://mng.bz/nP18 Summary
The solution is to add the pure elemental attributes to our previous version of the cold front program, as shown in the following listing. Listing 3.22 Cold front temperature function that works with scalars and arrays ❶ The elemental attribute makes the function compatible with both scalars and arrays. You can now invoke this function with one or more […]
To modify an input argument in-place, define it with the intent(in out) attribute, as shown in the following listing. Listing 3.21 A subroutine that modifies an input argument in-place ❶ Uses intent(in out) to indicate that a is both an input and an output ❷ We can modify a directly; it will be returned to the calling program or procedure. You […]
This section contains solutions to exercises in this chapter. Skip ahead if you haven’t worked through the exercises yet.
Finally, we get to put together the new function (from subsection 3.2.2) and subroutine (from subsection 3.3.3) in the main program of the tsunami simulator. In a nutshell, this program has the same functionality and behavior as the previous version from chapter 2. The key difference is that now we’ve abstracted away the code to […]
Both functions and subroutines can accept optional arguments. These are arguments that may be omitted by the caller, even if they’re specified in the procedure definition. To see optional arguments in action, let’s take our subroutine add from listing 3.13 and add an optional debug input parameter, as shown in listing 3.18. If this parameter is passed by the […]
When a procedure is defined to operate on scalar arguments, it’s relatively straightforward to make it work with array arguments as well. For example, recall our pure function sum from the previous subsection: Invoking this function as, say, sum(3, 5) will evaluate to 8. Is there a way to pass array arguments to this function such that it returns an array […]