How can I increase the decimal digits in the result of my program ? for example 50 or 80 digits .

 format long
 x=(pi);
 for i=1:10
    fx=cos(x(i))-3*x(i)+1;
    fxx=-sin(x(i))-3;
    x(i+1)=x(i)-(fx/fxx);
 end
 x(10)

% THE RESULT IS = 0.607101648103123

Answer 1

[Star Strider]

If you have the Symbolic Math Toolbox, you can use it. Another option is John D’Errico’s HPF - a big decimal class in the File Exchange.

[khalid boureeny]

Hi, Star Strider ...thanks a lot for your help ...

I do have Symbolic math toolbox , but the problem is I'm beginner and I don't know how ... can you modify this program for me ...

format long
x=(pi);
 for i=1:10
    fx=cos(x(i))-3*x(i)+1;
    fxx=-sin(x(i))-3;
    x(i+1)=x(i)-(fx/fxx);
 end
x(10)

% THE RESULT IS = 0.607101648103123

THANKS again , I really need that help ... [e-mail]

[Star Strider]

My pleasure.

Declare ‘x’ as as symbolic object, and the result will be symbolic with the precision defined by the digits function:

digits(50);
x= sym(pi);
 for i=1:10
    fx=cos(x(i))-3*x(i)+1;
    fxx=-sin(x(i))-3;
    x(i+1)=x(i)-(fx/fxx);
 end
x_10 = vpa(x(end))

x_10 =
0.60710164810312263122482837345049072888916774532395