A subroutine in Fortran 77 is a block of code that performs a specific task and can be called multiple times from different parts of a program. It can also have its own set of input parameters and return values.
A global spherical harmonic is a mathematical function that describes the variation of a physical quantity over the surface of a sphere. It is commonly used in geodesy and geophysics to represent the Earth's gravitational field, magnetic field, or topography.
To compute a global spherical harmonic in Fortran 77, you can use the subroutine designed specifically for this purpose. It typically takes in the required input parameters, such as the degree and order of the harmonic, and returns the corresponding value.
Using a subroutine for computing global spherical harmonics allows for modular and reusable code, reducing the need to rewrite the same code multiple times. It also makes the program more organized and easier to debug.
Yes, a Fortran 77 subroutine for computing global spherical harmonics can be adapted to compute other types of spherical harmonics, such as regional or local harmonics. This can be achieved by modifying the input parameters and the mathematical algorithm used in the subroutine.