Numerical Methods to solve Equation

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Razi Naji 2017-5-2

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评论： Razi Naji 2017-5-2

I am trying to solve the equation f(x) = x^3 + x - 1 , by using Bisection method within the interval [ 0 , 1] , i have succeeded to generate a code to solve this equation but by using " while " function for looping , i need some one to help me to solve it by using " for " function , could any one help me to do that ? the code is :

% Numerical Program to find the roots of % the equation f(x) = x^3 + x - 1 % By using Bisection Method within x = [ 0 , 1 ] , 1st method clear ; clc ; close all a = 0 ; b = 1 ; error = 1e-16 ; while ( b - a )/2 > error % by using " while " function c = ( a + b )/2 fc = c^3 + c - 1 ; if fc < 0 a = c ; else b = c ; end end

Thanks in advance Razi

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Answer 1

David Goodmanson 2017-5-2

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编辑：David Goodmanson 2017-5-2

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Hi Razi, the usual procedure is to use the 'break' condition

start with a value (an initial value may or may not be needed)
for n = 1:large
  do something, calculate a new value
  if <some condition is met>
    break
  end
  maybe do something else here
end
use the last computed value

The break procedure knocks you out of the for loop and terminates it.

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Razi Naji 2017-5-2

Ok David , thanks , i am trying now to solve it :-) , i will inform you if solved :)

Razi Naji 2017-5-2

Hello again David I did it , thanks for your hint :-) this is the code :

% Numerical Program to find the roots of % the equation f(x) = x^3 + x - 1 % By Bisection Method within x = [ 0 , 1 ] , 1st method clear ; clc ; close all a = 0 ; b = 1 ; n = 100 ; r = 0.6823278038 ; error = 0.5e-6 ; iteration = 0; for i=1:n iteration = iteration + 1 c = (a+b)/2 fc = c^3 + c - 1 ; if ( fc<0) a = c ; else b = c ; end if abs(c-r) > error continue else break end end

Best regards Razi

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