Calling UCVM With Fortran

Calling UCVM With Fortran

Calling UCVM using Fortran is a relatively trivial procedure. In order to do so, you must install UCVM as per the guide, including the etree and Proj.4 libraries. It is also necessary to download and install any community velocity models that you will be calling. UCVM requires those velocity models to be added to a configuration file so that they can be referenced within the application.

Once that initial set up is done, compiling and linking with gfortran is easy. You must include the UCVM library, the Proj.4 library, the e-tree library, as well as any velocity model libraries that you have compiled into UCVM. For CVM-H, please note that there are actually two libraries required: lvxapi and lgeo.

Because the default convention for calling C programs from Fortran automatically appends an underscore to the end of the function name, you must turn that off via a flag called "fno-underscoring". This will make the Fortran compiler try and find foo() instead of foo_().

As an example, suppose we have a Fortran file, example.f, that calls UCVM. We have compiled UCVM with CVM-S and CVM-H. The code to compile example.f would be as follows:

gfortran example.f -o ./example -L./ucvm-13.9.0/inst/lib -L./cvms/lib -L./cvmh-11.9.1/inst/lib -L./proj-4.8.0/inst/lib -L./euclid3-1.3/libsrc -lucvm -lcvms -lvxapi -lgeo -lproj -letree -fno-underscoring

The basic structure of how to call UCVM within Fortran is outlined in the example below.

Example Code

       program example
        

c UCVM Configuration Location

       CHARACTER(LEN=80) ucvmconf

c Model Name

      	CHARACTER(LEN=8) model 

c Number of points we're passing to ucvm_query

       INTEGER pts      
        

c The UCVM point data structure. c coord(1) is longitude c coord(2) is latitutde c coord(3) is depth

       TYPE :: ucvm_point_t

REAL*8 coord(3)

       END TYPE ucvm_point_t
        

c Generic property structure c Source is where it comes from c vp is P-wave velocity in m/s c vs is S-wave velocity in m/s c rho is density in kg/m^3

       TYPE :: ucvm_prop_t

INTEGER source

               REAL*8 vp
               REAL*8 vs
               REAL*8 rho
       END TYPE ucvm_prop_t
        

c Returned data structure

       TYPE :: ucvm_data_t
               REAL*8 surf
               REAL*8 vs30
               REAL*8 depth
               INTEGER domain
               REAL*8 shift_cr
               REAL*8 shift_gtl
               type(ucvm_prop_t) crust
               type(ucvm_prop_t) gtl
               type(ucvm_prop_t) cmb
       END TYPE ucvm_data_t
        

c For our example we'll query five points

       type(ucvm_point_t) point(5)

c And we'll get back five sets of material properties

       type(ucvm_data_t) returnData(5)
       

c Number of points is 5.

       pts = 5
        

c We'll start at -118, 34 at 0 depth and go down by 1000m c each step

       do 10 i = 1, 5

point(i)%coord(1) = -118

               point(i)%coord(2) = 34
               point(i)%coord(3) = (i - 1) * 1000

10 continue

c Where is our configuration file?

       ucvmconf = "/Users/davidgil/ucvm.conf" // CHAR(0)
        

c What model are we querying?

       model = "cvmsi" // CHAR(0)
        

c Initialize UCVM

       call ucvm_init(ucvmconf)
        

c Add the model to UCVM

       call ucvm_add_model(model)
        

c Query the model. Note that the number of points is passed c by value, not reference.

       call ucvm_query(%VAL(pts), point, returnData)
        
       print *, model, " results for lon -118, lat 34"
        

c Print out the results.

       do 20 i = 1, 5
		print *, "Depth ", (i - 1) * 1000
               print *, "Vs ", returnData(i)%crust%vs 
               print *, "Vp ", returnData(i)%crust%vp 
               print *, "Rho ", returnData(i)%crust%rho

20 continue

c Close UCVM now that we've queried the points

       call ucvm_finalize()
        
       end