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牛顿插值方法求解多项式的系数

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1. What is SIO ?

SIO is a library that provides _stream_ I/O which is what most Unix
programs do. As such it is a competitor to stdio.


2. Why would you care to use it ?

a. SIO is a little faster than stdio
b. SIO provides an easier-to-use interface (IMHO)
c. SIO is capable of using memory mapping for reading files if the operating
	system supports it.
d. If you have a program that uses read(2)/write(2) it is trivial
   to convert it to use SIO (just replace read with Sread and 
   write with Swrite)
e. You get source



3. Setting up the Stream I/O (SIO) library

There are 3 steps to the process:
	1) modifying the SIO configuration file (but you can skip this
		step if you are using one of the operating systems listed below).
	2) testing SIO
	3) installing the library and manpages


3.1. How to compile the Stream I/O (SIO) library

All the system-dependent stuff of SIO is placed in the sioconf.h file.
If your system is not listed below, you will need to read that file
to see what flags you need to set to properly compile SIO.

For the following systems, here is what you need to do:

	SunOS 4.x:
		make "DEFS=-DHAVE_MMAP -DHAVE_ONEXIT -DHAVE_MEMCPY -DHAVE_ISATTY"

	SunOS 5.x (aka Solaris 2.y):
		make "DEFS=-DHAVE_MMAP -DHAVE_ATEXIT -DHAVE_MEMCPY -DHAVE_ISATTY"
	(I don't have access to a system running Solaris 2.y so I have not
	tested this)

	Ultrix 4.x:
		make "DEFS=-DHAVE_MEMCPY -DHAVE_ATEXIT -DHAVE_ISATTY"

If your system is one of the above, then you can skip to the next subsection.
However, I should mention that the library compiles by default with
debugging enabled (i.e. uses the -g flag of cc). You can override this
by appending to the invocation of 'make' the argument "DEBUG=-O"

If your system is not among the above, then you will need to modify the
sioconf.h file. You do this by uncommenting the inclusion of
customconf.h. Then, you can override all constants/macros defined in
sioconf.h by defining them first in customconf.h.  Please read
sioconf.h for more information on what constants/macros can be
defined.

The Makefile has a header that explains what the Makefile can do.
The only flag that you may want to define is -DDEBUG which enables 
assertions in the SIO code (if an assertion fails, the program is 
terminated with an error message that lists the SIO file and line 
number where the error occured).


3.2. Testing SIO

After you have successfully compiled SIO, you can use the programs in
the "suite" directory to test the SIO functions.  Testing should be
done before installing the library.
The script testlib does everything; just type:

	testlib all

The script sprint_test (invoked by testlib) tests Sprint by using a variety 
of formats and comparing its output with that of an ANSI-compatible printf.
At least on Ultrix 4.1 and 4.2 this test fails because printf is not 
ANSI-compatible.
In such a case, you can test the rest of the SIO functions by typing:

	testlib all Sprint

(anything after the 'all' argument is interpreted as a function that
should not be tested).

The README file in the "suite" directory describes how to do a
few more tests that cannot be done automatically.


3.3. Installing the library and manpages

The 'make' command will create libsio.a in the current directory.
The Makefile includes an "install" target. Doing a 'make install' will 
cause the following:

a) libsio.a will be installed in LIBDIR
b) the necessary SIO header files will be installed in INCLUDEDIR
c) the SIO man pages will be installed in MANDIR

LIBDIR, INCLUDEDIR, and MANDIR are Makefile variables that you can edit in
the Makefile or override when you invoke 'make'.
Here is a sample command to install SIO:

	make install LIBDIR=/usr/local/lib INCLUDEDIR=/usr/local/include MANDIR=/usr/local/man/man3


4. Epilogue

Feel free to modify SIO to suit your needs. Please let me know of
any bugs you find.

If you want to distribute your modifications, please read the COPYRIGHT
file.  It basically says that you are free to redistribute as long as
you retain the original copyright notice and you make sure that your
modifications are identifiable. In order to achieve this I have
reserved the first 3 components of the version number (for example,
1.4.2) and you can identify your mods by appending another component to
that version number (for example, 1.4.2.A2). Also, if you distribute a
modified version of the library, you take full responsibility for any
bugs in the code (not just your code; the whole thing).