xref: /petsc/src/sys/classes/random/tutorials/ex1.c (revision 6a98f8dc3f2c9149905a87dc2e9d0fedaf64e09a)
1 
2 static char help[] = "Tests PetscRandom functions.\n\n";
3 
4 #include <petscsys.h>
5 
6 /* Usage:
7    mpiexec -n <np> ./ex1 -n <num_of_random_numbers> -random_type <type> -log_view
8                          -view_randomvalues <view_rank>
9                          -random_view ascii -random_view :filename
10 */
11 
12 int main(int argc,char **argv)
13 {
14   PetscInt       i,n = 1000,*values;
15   PetscRandom    rnd;
16   PetscScalar    value,avg = 0.0;
17   PetscErrorCode ierr;
18   PetscMPIInt    rank;
19   PetscInt       view_rank=-1;
20 #if defined(PETSC_USE_LOG)
21   PetscLogEvent  event;
22 #endif
23 
24   ierr = PetscInitialize(&argc,&argv,(char*)0,help);if (ierr) return ierr;
25   ierr = MPI_Comm_rank(PETSC_COMM_WORLD,&rank);CHKERRQ(ierr);
26   ierr = PetscOptionsGetInt(NULL,NULL,"-n",&n,NULL);CHKERRQ(ierr);
27   ierr = PetscOptionsGetInt(NULL,NULL,"-view_randomvalues",&view_rank,NULL);CHKERRQ(ierr);
28 
29   ierr = PetscRandomCreate(PETSC_COMM_WORLD,&rnd);CHKERRQ(ierr);
30   /* force imaginary part of random number to always be zero; thus obtain reproducible results with real and complex numbers */
31   ierr = PetscRandomSetInterval(rnd,0.0,1.0);CHKERRQ(ierr);
32   ierr = PetscRandomSetFromOptions(rnd);CHKERRQ(ierr);
33 
34   ierr = PetscMalloc1(n,&values);CHKERRQ(ierr);
35   for (i=0; i<n; i++) {
36     ierr = PetscRandomGetValue(rnd,&value);CHKERRQ(ierr);
37     avg += value;
38     if (view_rank == (PetscInt)rank) {
39       ierr = PetscPrintf(PETSC_COMM_SELF,"[%d] value[%D] = %6.4e\n",rank,i,(double)PetscRealPart(value));CHKERRQ(ierr);
40     }
41     values[i] = (PetscInt)(n*PetscRealPart(value) + 2.0);
42   }
43   avg = avg/((PetscReal)n);
44   if (view_rank == (PetscInt)rank) {
45     ierr = PetscPrintf(PETSC_COMM_SELF,"[%d] Average value %6.4e\n",rank,(double)PetscRealPart(avg));CHKERRQ(ierr);
46   }
47 
48   ierr = PetscSortInt(n,values);CHKERRQ(ierr);
49 
50   ierr = PetscLogEventRegister("Sort",0,&event);CHKERRQ(ierr);
51   ierr = PetscLogEventBegin(event,0,0,0,0);CHKERRQ(ierr);
52 
53   ierr = PetscRandomSeed(rnd);CHKERRQ(ierr);
54   for (i=0; i<n; i++) {
55     ierr      = PetscRandomGetValue(rnd,&value);CHKERRQ(ierr);
56     values[i] = (PetscInt)(n*PetscRealPart(value) + 2.0);
57     /* printf("value[%d] = %g\n",i,value); */
58   }
59   ierr = PetscSortInt(n,values);CHKERRQ(ierr);
60   ierr = PetscLogEventEnd(event,0,0,0,0);CHKERRQ(ierr);
61 
62   for (i=1; i<n; i++) {
63     if (values[i] < values[i-1]) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_PLIB,"Values not sorted");
64   }
65   ierr = PetscFree(values);CHKERRQ(ierr);
66   ierr = PetscRandomDestroy(&rnd);CHKERRQ(ierr);
67 
68   ierr = PetscFinalize();
69   return ierr;
70 }
71 
72 
73 
74 /*TEST
75 
76    test:
77 
78    test:
79       suffix: 2
80       nsize: 2
81       output_file: output/ex1_1.out
82 
83    test:
84       suffix: 3
85       args: -view_randomvalues 0
86 
87 TEST*/
88