Transcript PowerPoint-presentation

Ett javaprograms livscykel
public class Kvadratrot {
public static void main( String[] args){
double A= 9;
double x= 1, oldx;
do {
oldx= x;
x= 0.5*( A/x + x);
} while( oldx != x);
System.out.println("sqrt("+ A +")="+x);
}
}
Programstart
public class Kvadratrot {
public static void main( String[] args){
double A= 9;
double x= 1, oldx;
do {
main()-metoden körs
alltid vid programstart!
oldx= x;
x= 0.5*( A/x + x);
} while( oldx != x);
System.out.println("sqrt("+ A +")="+x);
}
}
Variabeldeklaration
public class Kvadratrot {
public static void main( String[] args){
double A= 9;
double x= 1, oldx;
do {
oldx= x;
x= 0.5*( A/x + x);
Deklarera A som ett
decimaltal och ge
den värdet 9.
} while( oldx != x);
System.out.println("sqrt("+ A +")="+x);
}
}
= betyder tilldelning
public class Kvadratrot {
public static void main( String[] args){
double A= 9;
double x= 1, oldx;
do {
oldx= x;
x= 0.5*( A/x + x);
} while( oldx != x);
System.out.println("sqrt("+ A +")="+x);
}
}
(double) A = 9
Vi kan deklarera flera variabler på en rad
public class Kvadratrot {
public static void main( String[] args){
double A= 9;
double x= 1, oldx;
do {
oldx= x;
x= 0.5*( A/x + x);
} while( oldx != x);
Deklarera x och oldx
som decimaltal och
ge x värdet 1.
System.out.println("sqrt("+ A +")="+x);
}
}
(double) A = 9
oldx har ännu inget värde…
public class Kvadratrot {
public static void main( String[] args){
double A= 9;
double x= 1, oldx;
do {
oldx= x;
x= 0.5*( A/x + x);
} while( oldx != x);
System.out.println("sqrt("+ A +")="+x);
}
}
(double) A = 9
(double) x = 1
(double) oldx = //okänt värde//
En iteration == upprepning
public class Kvadratrot {
public static void main( String[] args){
double A= 9;
double x= 1, oldx;
do {
oldx= x;
x= 0.5*( A/x + x);
Kör en itererad
undersekvens:
} while( oldx != x);
System.out.println("sqrt("+ A +")="+x);
}
}
(double) A = 9
(double) x = 1
(double) oldx = //okänt värde//
Ett javaprograms livscykel
public class Kvadratrot {
public static void main( String[] args){
double A= 9;
double x= 1, oldx;
do {
oldx= x;
x= 0.5*( A/x + x);
Det här är undersekvensen
- innesluten av { och }
} while( oldx != x);
System.out.println("sqrt("+ A +")="+x);
}
}
(double) A = 9
(double) x = 1
(double) oldx = //okänt värde//
Undersekvensens första sats
public class Kvadratrot {
public static void main( String[] args){
double A= 9;
double x= 1, oldx;
do {
Tilldela oldx värdet som
lagrats i x.
oldx= x;
x= 0.5*( A/x + x);
} while( oldx != x);
System.out.println("sqrt("+ A +")="+x);
}
}
(double) A = 9
(double) x = 1
(double) oldx = //okänt värde//
Värden i högerledet
public class Kvadratrot {
public static void main( String[] args){
double A= 9;
double x= 1, oldx;
do {
Variabler i högerled ersätts
med sina värden
oldx= x;
x= 0.5*( A/x + x);
} while( oldx != x);
System.out.println("sqrt("+ A +")="+x);
}
}
(double) A = 9
(double) x = 1
(double) oldx = //okänt värde//
Värden i högerledet
public class Kvadratrot {
public static void main( String[] args){
double A= 9;
double x= 1, oldx;
do {
Variabler i högerled ersätts
med sina värden
oldx= 1;
x= 0.5*( A/x + x);
} while( oldx != x);
System.out.println("sqrt("+ A +")="+x);
}
}
(double) A = 9
(double) x = 1
(double) oldx = //okänt värde//
Variabeln ersätts med sitt värde
public class Kvadratrot {
public static void main( String[] args){
double A= 9;
double x= 1, oldx;
värdet 1 lagras i oldx
do {
oldx= 1;
x= 0.5*( A/x + x);
} while( oldx != x);
System.out.println("sqrt("+ A +")="+x);
}
}
(double) A = 9
(double) x = 1
(double) oldx = //okänt värde//
Variabeln ersätts med sitt värde
public class Kvadratrot {
public static void main( String[] args){
double A= 9;
double x= 1, oldx;
värdet 1 lagras i oldx
do {
oldx= 1;
x= 0.5*( A/x + x);
} while( oldx != x);
System.out.println("sqrt("+ A +")="+x);
}
}
(double) A = 9
(double) x = 1
(double) oldx = 1
Uttryck i högerled
public class Kvadratrot {
public static void main( String[] args){
double A= 9;
double x= 1, oldx;
do {
oldx= x;
Högerledet är ett
matematiskt uttryck som
måste beräknas.
x= 0.5*( A/x + x);
} while( oldx != x);
System.out.println("sqrt("+ A +")="+x);
}
}
(double) A = 9
(double) x = 1
(double) oldx = 1
Uttryck i högerled
public class Kvadratrot {
public static void main( String[] args){
double A= 9;
double x= 1, oldx;
do {
Variabler ersätts med sina
värden
oldx= x;
x= 0.5*( 9/1 + 1);
} while( oldx != x);
System.out.println("sqrt("+ A +")="+x);
}
}
(double) A = 9
(double) x = 1
(double) oldx = 1
Uttryck i högerled
public class Kvadratrot {
public static void main( String[] args){
double A= 9;
double x= 1, oldx;
do {
…och deluttrycket
beräknas
oldx= x;
x= 0.5*( 10 );
} while( oldx != x);
System.out.println("sqrt("+ A +")="+x);
}
}
(double) A = 9
(double) x = 1
(double) oldx = 1
Uttryck i högerled
public class Kvadratrot {
public static void main( String[] args){
double A= 9;
double x= 1, oldx;
do {
…och hela uttrycket
beräknas
oldx= x;
x= 5;
} while( oldx != x);
System.out.println("sqrt("+ A +")="+x);
}
}
(double) A = 9
(double) x = 1
(double) oldx = 1
Uttryck i högerled
public class Kvadratrot {
public static void main( String[] args){
double A= 9;
double x= 1, oldx;
Slutligen lagras värdet i x
do {
oldx= x;
x= 5;
} while( oldx != x);
System.out.println("sqrt("+ A +")="+x);
}
}
(double) A = 9
(double) x = 5
(double) oldx = 1
Iterationsvillkor
public class Kvadratrot {
public static void main( String[] args){
double A= 9;
double x= 1, oldx;
do {
oldx= x;
Iterationssekvensen ska
köras om och om igen, så
länge som villkoret är sant
x= 0.5*( A/x + x);
} while( oldx != x);
System.out.println("sqrt("+ A +")="+x);
}
}
(double) A = 9
(double) x = 5
(double) oldx = 1
Iterationsvillkor
public class Kvadratrot {
public static void main( String[] args){
double A= 9;
double x= 1, oldx;
do {
oldx= x;
Sätt in variabelvärden:
x= 0.5*( A/x + x);
} while( 1 != 5);
System.out.println("sqrt("+ A +")="+x);
}
}
(double) A = 9
(double) x = 5
(double) oldx = 1
Iterationsvillkor
public class Kvadratrot {
public static void main( String[] args){
double A= 9;
double x= 1, oldx;
do {
oldx= x;
x= 0.5*( A/x + x);
Evaluera det logiska
uttrycket:
} while( true);
System.out.println("sqrt("+ A +")="+x);
}
}
(double) A = 9
(double) x = 5
(double) oldx = 1
Ett varv till…
public class Kvadratrot {
public static void main( String[] args){
double A= 9;
double x= 1, oldx;
do {
Eftersom det var sant, kör
vi ett varv till.
oldx= x;
x= 0.5*( A/x + x);
} while( oldx != x);
System.out.println("sqrt("+ A +")="+x);
}
}
(double) A = 9
(double) x = 5
(double) oldx = 1
Lite snabbare…
public class Kvadratrot {
public static void main( String[] args){
double A= 9;
double x= 1, oldx;
do {
oldx= x;
x= 0.5*( A/x + x);
} while( oldx != x);
System.out.println("sqrt("+ A +")="+x);
}
}
(double) A = 9
(double) x = 5
(double) oldx = 5
Lite snabbare…
public class Kvadratrot {
public static void main( String[] args){
double A= 9;
double x= 1, oldx;
do {
oldx= x;
x= 0.5*( A/x + x);
} while( oldx != x);
System.out.println("sqrt("+ A +")="+x);
}
}
(double) A = 9
(double) x = 3.4
(double) oldx = 5
Lite snabbare…
public class Kvadratrot {
public static void main( String[] args){
double A= 9;
double x= 1, oldx;
do {
oldx= x;
x= 0.5*( A/x + x);
(3.4 != 5) är true
} while( oldx != x);
System.out.println("sqrt("+ A +")="+x);
}
}
(double) A = 9
(double) x = 3.4
(double) oldx = 5
Lite snabbare…
public class Kvadratrot {
public static void main( String[] args){
double A= 9;
double x= 1, oldx;
do {
oldx= x;
x= 0.5*( A/x + x);
} while( oldx != x);
System.out.println("sqrt("+ A +")="+x);
}
}
(double) A = 9
(double) x = 3.4
(double) oldx = 3.4
Lite snabbare…
public class Kvadratrot {
public static void main( String[] args){
double A= 9;
double x= 1, oldx;
do {
oldx= x;
x= 0.5*( A/x + x);
} while( oldx != x);
System.out.println("sqrt("+ A +")="+x);
}
}
(double) A = 9
(double) x = 3.023529411764706
(double) oldx = 3.4
Lite snabbare…
public class Kvadratrot {
public static void main( String[] args){
double A= 9;
double x= 1, oldx;
do {
oldx= x;
x= 0.5*( A/x + x);
fortfarande true
} while( oldx != x);
System.out.println("sqrt("+ A +")="+x);
}
}
(double) A = 9
(double) x = 3.023529411764706
(double) oldx = 3.4
Lite snabbare…
public class Kvadratrot {
public static void main( String[] args){
double A= 9;
double x= 1, oldx;
do {
oldx= x;
x= 0.5*( A/x + x);
} while( oldx != x);
System.out.println("sqrt("+ A +")="+x);
}
}
(double) A = 9
(double) x = 3.023529411764706
(double) oldx = 3.023529411764706
Lite snabbare…
public class Kvadratrot {
public static void main( String[] args){
double A= 9;
double x= 1, oldx;
do {
oldx= x;
x= 0.5*( A/x + x);
} while( oldx != x);
System.out.println("sqrt("+ A +")="+x);
}
}
(double) A = 9
(double) x = 3.00009155413138
(double) oldx = 3.023529411764706
Lite snabbare…
public class Kvadratrot {
public static void main( String[] args){
double A= 9;
double x= 1, oldx;
do {
oldx= x;
x= 0.5*( A/x + x);
fortfarande true
} while( oldx != x);
System.out.println("sqrt("+ A +")="+x);
}
}
(double) A = 9
(double) x = 3.00009155413138
(double) oldx = 3.023529411764706
Lite snabbare…
public class Kvadratrot {
public static void main( String[] args){
double A= 9;
double x= 1, oldx;
do {
oldx= x;
x= 0.5*( A/x + x);
} while( oldx != x);
System.out.println("sqrt("+ A +")="+x);
}
}
(double) A = 9
(double) x = 3.00009155413138
(double) oldx = 3.00009155413138
Lite snabbare…
public class Kvadratrot {
public static void main( String[] args){
double A= 9;
double x= 1, oldx;
do {
oldx= x;
x= 0.5*( A/x + x);
} while( oldx != x);
System.out.println("sqrt("+ A +")="+x);
}
}
(double) A = 9
(double) x = 3.000000001396984
(double) oldx = 3.00009155413138
Lite snabbare…
public class Kvadratrot {
public static void main( String[] args){
double A= 9;
double x= 1, oldx;
do {
oldx= x;
x= 0.5*( A/x + x);
fortfarande true
} while( oldx != x);
System.out.println("sqrt("+ A +")="+x);
}
}
(double) A = 9
(double) x = 3.000000001396984
(double) oldx = 3.00009155413138
Lite snabbare…
public class Kvadratrot {
public static void main( String[] args){
double A= 9;
double x= 1, oldx;
do {
oldx= x;
x= 0.5*( A/x + x);
} while( oldx != x);
System.out.println("sqrt("+ A +")="+x);
}
}
(double) A = 9
(double) x = 3.000000001396984
(double) oldx = 3.000000001396984
Lite snabbare…
public class Kvadratrot {
public static void main( String[] args){
double A= 9;
double x= 1, oldx;
do {
oldx= x;
x= 0.5*( A/x + x);
} while( oldx != x);
System.out.println("sqrt("+ A +")="+x);
}
}
(double) A = 9
(double) x = 3.0
(double) oldx = 3.000000001396984
Lite snabbare…
public class Kvadratrot {
public static void main( String[] args){
double A= 9;
double x= 1, oldx;
do {
oldx= x;
x= 0.5*( A/x + x);
fortfarande true
} while( oldx != x);
System.out.println("sqrt("+ A +")="+x);
}
}
(double) A = 9
(double) x = 3.0
(double) oldx = 3.000000001396984
Lite snabbare…
public class Kvadratrot {
public static void main( String[] args){
double A= 9;
double x= 1, oldx;
do {
oldx= x;
x= 0.5*( A/x + x);
} while( oldx != x);
System.out.println("sqrt("+ A +")="+x);
}
}
(double) A = 9
(double) x = 3.0
(double) oldx = 3.0
Lite snabbare…
public class Kvadratrot {
public static void main( String[] args){
double A= 9;
double x= 1, oldx;
do {
oldx= x;
x= 0.5*( A/x + x);
} while( oldx != x);
System.out.println("sqrt("+ A +")="+x);
}
}
(double) A = 9
(double) x = 3.0
(double) oldx = 3.0
Lite snabbare…
public class Kvadratrot {
public static void main( String[] args){
double A= 9;
double x= 1, oldx;
do {
oldx= x;
x= 0.5*( A/x + x);
Nu är det false!
} while( oldx != x);
System.out.println("sqrt("+ A +")="+x);
}
}
(double) A = 9
(double) x = 3.0
(double) oldx = 3.0
Lite snabbare…
public class Kvadratrot {
public static void main( String[] args){
double A= 9;
double x= 1, oldx;
do {
oldx= x;
x= 0.5*( A/x + x);
} while( oldx != x);
Iterationen avslutad.
Ett uttryck med strängar
måste evalueras:
System.out.println("sqrt("+ A +")="+x);
}
}
(double) A = 9
(double) x = 3.0
(double) oldx = 3.0
Lite snabbare…
public class Kvadratrot {
public static void main( String[] args){
double A= 9;
double x= 1, oldx;
do {
oldx= x;
x= 0.5*( A/x + x);
} while( oldx != x);
In med variabelvärden:
System.out.println("sqrt("+ 9 +")="+ 3.0);
}
}
(double) A = 9
(double) x = 3.0
(double) oldx = 3.0
Lite snabbare…
public class Kvadratrot {
public static void main( String[] args){
double A= 9;
double x= 1, oldx;
do {
oldx= x;
x= 0.5*( A/x + x);
} while( oldx != x);
”beräkna”
System.out.println("sqrt(9)=3.0");
}
}
(double) A = 9
(double) x = 3.0
(double) oldx = 3.0
Utskrift…
public class Kvadratrot {
public static void main( String[] args){
double A= 9;
double x= 1, oldx;
do {
oldx= x;
x= 0.5*( A/x + x);
} while( oldx != x);
Skriv ut
System.out.println("sqrt(9)=3.0");
}
}
(double) A = 9
(double) x = 3.0
(double) oldx = 3.0
sqrt(9)=3.0
Avslut…
public class Kvadratrot {
public static void main( String[] args){
double A= 9;
double x= 1, oldx;
do {
oldx= x;
x= 0.5*( A/x + x);
} while( oldx != x);
System.out.println("sqrt(9)=3.0");
}
}
(double) A = 9
(double) x = 3.0
(double) oldx = 3.0
sqrt(9)=3.0
Mycket skrik för lite ull
sade gumman som klippte grisen
45 slides för att beräkna roten ur 9, eller
33.1 millisekunder för datorn att köra samma program.