3-3 FINDING USEFUL ROUTINES
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Writing a good procedure may be a time consuming task, and require
a lot of expertise. It may require a study of the algorithms involved,
taking into consideration numerical and programming issues and then
programming and careful debugging.
Using procedures written by other people saves time and usually can
improve your code. However you have to excercize some caution, it may
make your programs non-redistributable, also some sources may contain
code that is of low-quality from the numerical analytic point of view.
Netlib
------
A very large collection of good routines and information by various
authors. A quick reference index can be found in appendix E.
From the Netlib FAQ:
The Netlib repository contains freely available software, documents,
and databases of interest to the numerical, scientific computing, and
other communities.
The repository is maintained by AT&T Bell Laboratories, the University
of Tennessee and Oak Ridge National Laboratory, and by colleagues
world-wide. The collection is replicated at several sites around the
world, automatically synchronized, to provide reliable and network
efficient service to the global community.
Netlib mirror site URL
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Tennessee, USA http://www.netlib.org/
New Jersey, USA http://netlib.bell-labs.com/netlib/master/readme.html
Bergen, Norway http://www.netlib.no/netlib/master/readme.html
Hensa, Kent, UK http://www.hensa.ac.uk/ftp/mirrors/netlib/master
ZIB, Germany ftp://ftp.zib.de/netlib/
NCHC, Taiwan ftp://ftp.nchc.gov.tw/netlib/
Japan http://phase.etl.go.jp/netlib/
Access method Directions
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World Wide Web (WWW) URL: http://www.netlib.org/
email for a contents summary and instructions
Send the message: send index
to: netlib@netlib.org
Anonymous ftp to: ftp.netlib.org
gopher Point your gopher browser to: gopher.netlib.org
xnetlib Not recommended
cd-rom Netlib (other than toms) is available on CD-ROM
NUMERICAL RECIPES
-----------------
A collection of routines distributed commercially in source code format.
Performs a wide range of numerical tasks, for example:
Linear Algebraic System / Interpolation /
Integration / Approximation / Special Functions /
Random Numbers / Sorting / Root Finding /
Minimization / Eigensystems /FFT and applications /
Statistics / Data Modeling / ODE's / ...
Numerical Recipes are harshly criticized by numerical analysts for the
quality of the code, algorithms and numerics, and for using algorithms
long ago superseded by better ones. A common opinion is that the routines
shouldn't be used for serious work, as they can give inaccurate or even
plain wrong results without any warning.
Numerical Analysis being a difficult subject to master, NR established
a wide clientele by offering a relatively cheap and very easy to use
alternative. Many users of mathematical software knows very little on
Numerical Analysis and can't judge its quality, or what lack of it means.
A book containing basic theory and description of the routines is :
NUMERICAL RECIPES in FORTRAN
The art of scientific computing
Second edition
William H. Press / Saul A. Teukolsky
William T. Vetterling / Brian P. Plannery
Cambridge University Press
ISBN 0-521-43064-X
The routines themselves are distributed in an archived form on a PC or
MAC diskette. An examples book is also available.
The first author made a gopher index of the somewhat old SLATEC library,
so it is not a surprise that his Runge-Kutta integrator seems similar
to the older routines by Shampine. Less care for important details like
the control of the step-size made his routine perform unreliably on a
simple non-stiff orbit calculation. Since there are free professional
integrators that offer so much more functionality, we just switched to
one of them.
Numerical Algorithms Group (NAG)
--------------------------------
A commercial routine library, you link it with your
compiled program.
Visual Numerics (formerly IMSL)
-------------------------------
A commercial routine library, you link it with your
compiled program.
MATLAB
------
Matlab is one of many interactive packages, some of them free
(see the Numerical Analysis FAQ).
Remember that such interactive packages may run up to 100 times
slower than compiled code (ref: Mathlab News and Notes), this
figure may be even higher when compared with good Fortran code.
NIST
----
Statlib
-------
NCAR
----
A much more important factor in the social movement than those already mentioned was the ever-increasing influence of women. This probably stood at the lowest point to which it has ever fallen, during the classic age of Greek life and thought. In the history of Thucydides, so far as it forms a connected series of events, four times only during a period of nearly seventy years does a woman cross the scene. In each instance her apparition only lasts for a moment. In three of the four instances she is a queen or a princess, and belongs either to the half-barbarous kingdoms of northern Hellas or to wholly barbarous Thrace. In the one remaining instance208— that of the woman who helps some of the trapped Thebans to make their escape from Plataea—while her deed of mercy will live for ever, her name is for ever lost.319 But no sooner did philosophy abandon physics for ethics and religion than the importance of those subjects to women was perceived, first by Socrates, and after him by Xenophon and Plato. Women are said to have attended Plato’s lectures disguised as men. Women formed part of the circle which gathered round Epicurus in his suburban retreat. Others aspired not only to learn but to teach. Arêtê, the daughter of Aristippus, handed on the Cyrenaic doctrine to her son, the younger Aristippus. Hipparchia, the wife of Crates the Cynic, earned a place among the representatives of his school. But all these were exceptions; some of them belonged to the class of Hetaerae; and philosophy, although it might address itself to them, remained unaffected by their influence. The case was widely different in Rome, where women were far more highly honoured than in Greece;320 and even if the prominent part assigned to them in the legendary history of the city be a proof, among others, of its untrustworthiness, still that such stories should be thought worth inventing and preserving is an indirect proof of the extent to which feminine influence prevailed. With the loss of political liberty, their importance, as always happens at such a conjuncture, was considerably increased. Under a personal government there is far more scope for intrigue than where law is king; and as intriguers women are at least the209 equals of men. Moreover, they profited fully by the levelling tendencies of the age. One great service of the imperial jurisconsults was to remove some of the disabilities under which women formerly suffered. According to the old law, they were placed under male guardianship through their whole life, but this restraint was first reduced to a legal fiction by compelling the guardian to do what they wished, and at last it was entirely abolished. Their powers both of inheritance and bequest were extended; they frequently possessed immense wealth; and their wealth was sometimes expended for purposes of public munificence. Their social freedom seems to have been unlimited, and they formed combinations among themselves which probably served to increase their general influence.321 The old religions of Greece and Italy were essentially oracular. While inculcating the existence of supernatural beings, and prescribing the modes according to which such beings were to be worshipped, they paid most attention to the interpretation of the signs by which either future events in general, or the consequences of particular actions, were supposed to be divinely revealed. Of these intimations, some were given to the whole world, so that he who ran might read, others were reserved for certain favoured localities, and only communicated through the appointed ministers of the god. The Delphic oracle in particular enjoyed an enormous reputation both among Greeks and barbarians for guidance afforded under the latter conditions; and during a considerable period it may even be said to have directed the course of Hellenic civilisation. It was also under this form that supernatural religion suffered most injury from the great intellectual movement which followed the Persian wars. Men who had learned to study the constant sequences of Nature for themselves, and to shape their conduct according to fixed principles of prudence or of justice, either thought it irreverent to trouble the god about questions on which they were competent to form an opinion for themselves, or did not choose to place a well-considered scheme at the mercy of his possibly interested responses. That such a revolution occurred about the middle of the fifth century B.C., seems proved by the great change of tone in reference to this subject which one perceives on passing from Aeschylus to Sophocles. That anyone should question the veracity of an oracle is a supposition which never crosses the mind of the elder dramatist. A knowledge of augury counts among the greatest benefits222 conferred by Prometheus on mankind, and the Titan brings Zeus himself to terms by his acquaintance with the secrets of destiny. Sophocles, on the other hand, evidently has to deal with a sceptical generation, despising prophecies and needing to be warned of the fearful consequences brought about by neglecting their injunctions. The stranger had a pleasant, round face, with eyes that twinkled in spite of the creases around them that showed worry. No wonder he was worried, Sandy thought: having deserted the craft they had foiled in its attempt to get the gems, the man had returned from some short foray to discover his craft replaced by another. “Thanks,” Dick retorted, without smiling. When they reached him, in the dying glow of the flashlight Dick trained on a body lying in a heap, they identified the man who had been warned by his gypsy fortune teller to “look out for a hidden enemy.” He was lying at full length in the mould and leaves. "But that is sport," she answered carelessly. On the retirement of Townshend, Walpole reigned supreme and without a rival in the Cabinet. Henry Pelham was made Secretary at War; Compton Earl of Wilmington Privy Seal. He left foreign affairs chiefly to Stanhope, now Lord Harrington, and to the Duke of Newcastle, impressing on them by all means to avoid quarrels with foreign Powers, and maintain the blessings of peace. With all the faults of Walpole, this was the praise of his political system, which system, on the meeting of Parliament in the spring of 1731, was violently attacked by Wyndham and Pulteney, on the plea that we were making ruinous treaties, and sacrificing British interests, in order to benefit Hanover, the eternal millstone round the neck of England. Pulteney and Bolingbroke carried the same attack into the pages of The Craftsman, but they failed to move Walpole, or to shake his power. The English Government, instead of treating Wilkes with a dignified indifference, was weak enough to show how deeply it was touched by him, dismissed him from his commission of Colonel of the Buckinghamshire Militia, and treated Lord Temple as an abettor of his, by depriving him of the Lord-Lieutenancy of the same county, and striking his name from the list of Privy Councillors, giving the Lord-Lieutenancy to Dashwood, now Lord Le Despencer. "I tell you what I'll do," said the Deacon, after a little consideration. "I feel as if both Si and you kin stand a little more'n you had yesterday. I'll cook two to-day. We'll send a big cupful over to Capt. McGillicuddy. That'll leave us two for to-morrer. After that we'll have to trust to Providence." "Indeed you won't," said the Surgeon decisively. "You'll go straight home, and stay there until you are well. You won't be fit for duty for at least a month yet, if then. If you went out into camp now you would have a relapse, and be dead inside of a week. The country between here and Chattanooga is dotted with the graves of men who have been sent back to the front too soon." "Adone do wud that—though you sound more as if you wur in a black temper wud me than as if you pitied me." "Wot about this gal he's married?" "Don't come any further." "Davy, it 'ud be cruel of us to go and leave him." "Insolent priest!" interrupted De Boteler, "do you dare to justify what you have done? Now, by my faith, if you had with proper humility acknowledged your fault and sued for pardon—pardon you should have had. But now, you leave this castle instantly. I will teach you that De Boteler will yet be master of his own house, and his own vassals. And here I swear (and the baron of Sudley uttered an imprecation) that, for your meddling knavery, no priest or monk shall ever again abide here. If the varlets want to shrieve, they can go to the Abbey; and if they want to hear mass, a priest can come from Winchcombe. But never shall another of your meddling fraternity abide at Sudley while Roland de Boteler is its lord." "My lord," said Edith, in her defence, "this woman has sworn falsely. The medicine I gave was a sovereign remedy, if given as I ordered. Ten drops would have saved the child's life; but the contents of the phial destroyed it. The words I uttered were prayers for the life of the child. My children, and all who know me, can bear witness that I have a custom of asking His blessing upon all I take in hand. I raised my eyes towards heaven, and muttered words; but, my lord, they were words of prayer—and I looked up as I prayed, to the footstool of the Lord. But it is in vain to contend: the malice of the wicked will triumph, and Edith Holgrave, who even in thought never harmed one of God's creatures, must be sacrificed to cover the guilt, or hide the thoughtlessness of another." "Aye, Sir Treasurer, thou hast reason to sink thy head! Thy odious poll-tax has mingled vengeance—nay, blood—with the cry of the bond." HoME古一级毛片免费观看
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