Fortran

The tsunami simulator source code is now made of two source files: the main program (tsunami.f 90), which defines the top-level simulation loop, and the finite difference module (mod_diff.f 90). In all our work so far, we’ve always compiled our Fortran programs from single-source files. How do you compile a program that’s defined across multiple […]

Here, we’ll focus on writing a brand new module, and defining the finite difference function in it. When we’re done, we’ll be able to import this function from the module and use it in the main program. Start by opening a brand-new source file, mod_diff.f 90. Once you’re in the file, you can define the module scope […]

Before we begin, let’s see what a custom module may look like on the inside, and how its building blocks work (figure 4.3). Figure 4.3 Structure of a custom Fortran module Every Fortran module is defined with a pair of module/end module statements. Modules can’t have any executable code on their own. Instead, they’re used to declare data […]

You’re now ready to tackle the next big item–writing your own custom module. Let’s do so by implementing it directly in the tsunami simulator. Recall that in the previous chapter we created two procedures: We defined both of these procedures in the main program. This worked well because our simulator was still rather simple. However, […]

In chapter 2, I mentioned that variables of built-in types can be explicitly and portably declared using specific type kinds. Type kind parameters determine the space that numeric variables occupy in memory, which in turn limits the range for integers, and the range and precision for real and complex numbers. Most Fortran compilers by default […]

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 […]