notes

diehard随机数测试套件的C程序代码

Some of the c programs work differently than their fortran counter
parts. This results in differences in the test result on the same
file. Most of the differences are insignificant. Following is the
detail (In the following text, sqeez.f, ..., means sqeez, ..., test
in diehard.f).

1. The squeez.c stops squeezing after 48 trials while sqeez.f
   continues until k is squeezed to 1. There should not be any
   significant difference in the test result.

2. The c programs convert the numbers from the input file into
   unsigned integers between 0 to 2**32. The fortran programs 
   convert them into integers between -2**31 to 2**31. This causes
   differences in the result of some tests. But this difference 
   should not be significant if these numbers are iid uniform. The 
   affected tests are: craptest, 3dsphere test, .... 

3. Mindist.f does not work correctly on SUN . It is supposed to sort vector 
   x but it actually sorts y. After changes are made, it gives identical
   result as mindist.c. Without change. it produces worng result.

4. The way 3dsphere.c gets points is different from the way used by its 
   fortan counterpart. The difference in test result is insignificant. 

5. The p-values given by c programs are equal to 1 minus p-values given by
   their fortran counterparts.  

6. Binary matrix test 31, 32 and 6x8 are combined as binrnk(). For example 
      binrnk(filename, "6x8")
   will perform 6 x 8 test on filename. Other tests are called in the same
   way. The result of 32x32 is slightly different from its fortran counter 
   part. This is because 32x32 is called after 31x31 in fortran program. 
   The file is closed and reopened. However, there are unused observations
   from the previous test. So 32x32 does not read the file immediately to 
   get obs.. The c program starts from the begining of the file whenever it 
   is reopened. The difference is insignificant. It exists in all tests that
   reopen files when it is executed.

7. The differences between c and fortran version of the count-the-1s tests 
   are due to the precision of computation. 

8. Difference between cdbday.c and cdbday.f is small.

9. When c programs read a binary file written by a fortran program. It reads
   in some garbages at some places. It is hard to take care of this problem
   if we do not know how the binary file is written. Anyway it should not 
   cause significant differnce in the test results on the file. 

10 diehard.c is the driver program. A "Makefile" is included so that the make           utility can be used to facilitate the compilation and updating of 
   the programs. So to compile or recompile the programs after changes, one 
   only needs to type "make". It yields a executable file by the name 
   "diehard".  

11 Because it is easy to redirect the output. diehard writes the result
   only to standard output (screen). 

12 Some types are defined in the file "header.c". uniform should be defined 
   as unsigned. counter can be either unsigned or long int (it needs 32 bits).