二分法求函数值的Pascal实现

用二分法求在（a,b)上单调的函数近似值

第八行的表达式可更改，第三行的kexi决定的精度，小数值计算可将第五行的extended更为real或double

PROGRAM EQUANTION (input,output);

CONST

kexi=0.0000001;

VAR

a,b,c:extended;

FUNCTION fx(x:extended):extended;

BEGIN

fx:=ln(x)/ln(2);

END;

BEGIN

writeln('Please input a and b’，' Produced BY Chaos')

read(a,b);

c:=(a+b)/2;

IF fx(c)=0

THEN writeln('x=',c)

ELSE Repeat

IF fx(a)*fx(c)<0

THEN b:=c

ELSE a:=c;

UNTIL abs(a-b)<kexi;

IF fx(c)<>0

THEN writeln('x=',a);

END.