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Functionspackageupcomputationwhendoweusethem?Allthetime.

Writesomesimplecodetoachieveagoal

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Toputtherectangleindifferentplaces,weparameterizetheposition,thatis,use

inputtothefunctiontoplacetherectangle

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Nowwequitthinkingofdrawingarectangle,butnowthinkofplacinga50x50rectangle

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Returntolastlecturefortwoslidesonthetopicofparameters

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Parameters: Customize each function call

to a specific situation they are the input tothe function

Parameters are the names of the inputvalues used inside of the procedure body

Arguments are the values from outside tobe used for each of the parameters

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NoticethatiftheDEFINITIONhasnparameters,theCALLneedsnarguments

Theparametersandargumentscorrespond

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Inside of the function, the

parameter, e.g. xbase, is

declared and initialized to thecorresponding argument, e.g. 80.

Then, the definition uses it, e.g.

rect(80, 40+10, 20, 40)

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Parametersareautomaticallydeclared(andinitialized)onacall,andremaininexistence

aslongasthefunctionremainsunfinished Whenthefunctionends,theparameters

vanish,onlytoberecreatedonthenextcall Itiswisetochooseparameternames,e.g.

xbasethataremeaningfultoyou

Ichosexbaseastheorientationpointofthefigureinthexdirection NoticethatIusedthatnamealot,andthemeaningtomeremainedthesame

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Wesaid(itwasthe2nddayofclass)thatafunctiondefinitionhas3parts:name,

params,body

Nameiscritical:itnamestheconceptcreatedbythefunction

Parametersarecritical:theycustomizeafunctiontomanycases

Bodyiscritical:itdefineshowthefunctionworks Functionuses(calls)have2parts:name,args Nameiscritical:sayswhatconceptyouwilluse Argumentsarecritical:sayshowthiscasehandled

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LawrenceSnyderUniversityofWashington,Seattle

Lawrence Snyder 2004

Bits are IT

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Analogueinformationdirectlyappliesphysicalphenomena,e.g.vinylrecords

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Samplingthewave

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Analogisneededfortherealworld

Digitalisbestforinformationworld

Canbemodified,enhanced,remixed,etc Shared,storedpermanently,reproduced,

1/31/11 2010 Larry Snyder, CSE 12

Device DriverMemory A/D Converter

Device DriverMemory D/A Converter

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Factsaboutphysicalrepresentation: Informationisrepresentedbythepresenceorabsenceofaphysicalphenomenon(PandA)

Holepunchedinacard;nohole[Hollerith] Dogbarksinthenight;nobarkinginthenight[Holmes] Wireiselectricallycharged;wireisneutral ETC

Abstractallthesecaseswith0and1;itunifiesthemsowedonthavetoconsiderthedetails

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Binaryissufficientfornumberrepresentation(place/value)andarithmetic

Thenumberbaseis2,insteadof10 Binaryadditionisjustlikeadditioninanyotherbaseexceptithasfewercasesbetterforcircuits

Allarithmeticandstandardcalculationshavebinaryequivalents

Weconclude:bitsworkforquantities

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Bytesillustratethatbitscanbegroupedinsequencetogenerateuniquepatterns

2bitsinsequence,22=4patterns:00,01,10,11 4bitsinsequence,24=8patterns:0000,0001, 8bitsinsequence,28=256patterns:00000000,

ASCIIgroups8bitsinsequence

Theyseemtobeassignedintelligently,

buttheyrejustpatterns

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ComparebinaryarithmetictoASCII Binaryencodesthepositionstomakeusingtheinformation(numbers)easy,likeforaddition

ASCIIassignssomepatterntoeachletter

Givenanyfinitesetofthingscolors,computeraddresses,Englishwords,etc.

WemightfigureoutasmartwaytorepresentthemasbitscolorscangivelightintensityofRGB

Wecanjustassignpatterns,andmanipulatethembypatternmatchingredcanbe00000001,darkred00000010,etc.

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Whatdoesthisrepresent:00000000111100010000100000100000?

Youdontknowuntilyouhowitwasencoded Asabinarynumber:15,796,256 Asacolor,RGB(241,8,32) Asacomputerinstruction:Add1,7,17 AsASCII:nubs IPAddress:0.241.8.32 Hexadecimalnumber:00F10820 toinfinityandbeyond

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Thisistheprinciple:

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Bias-free Universal Medium Principle:

Bits can represent all discrete information;

bits have no inherent meaning

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Analoginformationmustbemadediscrete(digitized)beforeitcanbeprocessedby

computersthisisdonebyA/Dconverter

Thereverseprocessletsushearit:D/A Bitsaresufficienttoencodealldiscrete

information Bitshavenoinherentmeaning,sotheycan

beusedforanything

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