隨筆
隨筆，聊天
博文
(2025-03-22 07:23:19)
ZT匈牙利數學家波利亞(GeorgePólya)曾經講過一個跟黎曼猜想有關的小故事，故事的主角是英國數學家哈代與丹麥數學家玻爾。這兩位在黎曼猜想研究中作出過成果的數學家當然都對黎曼猜想懷有濃厚興趣。有一段時間，哈代常常利用假期訪問玻爾，一起討論黎曼猜想，直到假期將盡才匆匆趕回英國。結果有一次，當哈代又必須匆匆趕回英國時，很不幸地發現碼頭上隻剩下一[閱讀全文]
(2025-03-14 05:07:56)
(2024-01-25 03:23:31)
1.publicstaticStringremoveBlankAndDot(Stringtarget){if(target!=null){intlen=target.length();//movethisoutofloop,moreefficientStringBufferbuf=newStringBuffer(len);//usingknownsizetocreateStringBuffer,moreefficient,defaultsizeis16char.//Ifthelen>16,incorrectdesignwillforceStringBuffertoresize.//Usingpre-sizeCollectionsismoreefficient,forexample://faster,assumingexpecting1000-2000elements://Mapm=n...[閱讀全文]
(2024-01-25 03:11:53)
1.publicstaticStringremoveBlankAndDot(Stringtarget){if(target!=null){StringBufferbuf=newStringBuffer();for(intii=0;ii<target.length();ii++){charc=target.charAt(ii);if(c!=''&&c!='.')buf.append(c);}returnbuf.toString();}returnnull;}2.publicclassDataLogger{privatestaticPrintStreamerr=System.err;privatestaticStringfilePath="log";privatestaticStringfileName="my...[閱讀全文]
(2024-01-25 03:05:44)
1..class{
padding-left:3px;
margin-right:6px;
padding-top:10px;
padding-right:9px;
margin-left:6px;
background-image:url('images/happy.jpg');
background-position:bottom;
background-repeat:repeat-x;
background-color:#E2CCCC;
}
-------------------------------
CSSShorthandisusedtoturnmanyCSSpropertiesintoonetomakethefilesizesmaller
andaclean...[閱讀全文]
padding-left:3px;
margin-right:6px;
padding-top:10px;
padding-right:9px;
margin-left:6px;
background-image:url('images/happy.jpg');
background-position:bottom;
background-repeat:repeat-x;
background-color:#E2CCCC;
}
-------------------------------
CSSShorthandisusedtoturnmanyCSSpropertiesintoonetomakethefilesizesmaller
andaclean...[閱讀全文]
(2024-01-18 05:59:56)
1.
varPerson={
"firstname":"Mike",
"middlename":"D.",
...,
}
for(variteminPerson){
document.writeln(Person[item]);
}
------------------------------------
for-inloopisusedtoiterateovernonarrayobject.
Itmakesnoguaranteeabouttheorderofenumerateditem.
Forsequentialintegers,weshoulduseanarray;otherwise,useanobject.<...[閱讀全文]
varPerson={
"firstname":"Mike",
"middlename":"D.",
...,
}
for(variteminPerson){
document.writeln(Person[item]);
}
------------------------------------
for-inloopisusedtoiterateovernonarrayobject.
Itmakesnoguaranteeabouttheorderofenumerateditem.
Forsequentialintegers,weshoulduseanarray;otherwise,useanobject.<...[閱讀全文]
(2024-01-18 05:49:02)
CANDC++TESTING(INTERMEDIATE)1.Explainthefollowing:(1)structstr*(*block())[8];(2)double(*(*func)())[2][6];2.What'sobjectID?What'spersistentobject?Howtocreatepersistentobject?3.What’sthetype(span)ofapointer?Inthefollowingcode:classA:publicB{…};Aa;B*pb=&a;A*pa=&a;What’sdifferencebetweenpbandpa?4.Whyintheiostreamlibrarythedesignerdefined“operatorvoid*()”f...[閱讀全文]
(2024-01-18 05:41:52)
CANDC++TESTING(BASIC)1.What'sprecedence?What'sassociativity?2.What'slvalue?What'srvalue?Why(x=y)=zisillegalinC?3.What'ssignatureoffunction?What'sdifferenceofsignaturesinCandC++?4.What'soverloadingoffunction?What'smangling?5.WhatarestaticvariableandstaticfunctioninC?Whataretheirscopes?6.What'sdifferencebetweenreferenceandpointer?WhyreferenceisneededinC++?7.Howtoa...[閱讀全文]
(2024-01-03 12:02:49)
Whatdomathteacherseat?Squaremeals. Whydidthecalfhatehisschoolpicture?Hiscow-lickwasstickingup. WhattimeofdayAdamwascreated?AlittlebeforeEve. WhatdoyoucallaK9whogetslostonHalloween?A“wherewolf(werewolf). Whydidthegranddaughterthinkshelivedinheaven?Becausehergrandmatoldhershewasanangel. Whyisthepianosohardtoopen?Becausethekeysarealreadyinside. Whydokittensknowsomuchaboutchurch?Th...[閱讀全文]
(2023-12-17 13:29:56)
有人認為代數幾何是很難理解的數學。本文想通俗地介紹它的一些基本概念。在平麵上有一單位圓,x^2+y^2=1.設圓上的點的座標為(1/√2,1/√2),(1/√2,-1/√2)。對應在座標軸上可表示如下：這就構成座標環（Ring）。
—---------(-1/√2)-----------------(1/√2)-----------(3/√2)-----
在單位圓上取值的函數f1(x,y)=y－－－[(1/√2,1/√2),(1/√2,-1/√2)]&m...[閱讀全文]
