How do I simplify a symbolic expression into numeric output?

My answer for a calculation is:

ans =

(3060513257434037*x1^2)/1125899906842624 + x1 + 
(3060513257434037*x2^2)/1125899906842624 + x2 + 
 4186413164276661/1125899906842624

How can I get MATLAB to display the answer with the fraction evaluated in decimal format?

[Mithlesh Kumar]

As you have used symbolic function, to get output displayed in decimal format use "vpa" command.

[Ganesh P. Prajapat]

This comes out of the 'subs' command when 'syms' is associated. The simple way to have a simplified solution is, use vpa(x,d) command where x gets simplified upto d digits.

Answer 1

[Walter Roberson]

Use vpa() to convert fractions and numeric constants (such as Pi) into symbolic fixed-point arithmetic, such as might be used for further symbolic processing.

Use double() to convert fractions and numeric constants (such as Pi) into binary floating point arithmetic, such as might be used for further processing at the Matlab level.

[Christopher Creutzig]

Symbolic does not use fixed-point arithmetic, it uses variable-precision floating-point arithmetic (in addition to exact arithmetic).

[Luis Enciso]

I had the same problem, but vpa is nice for me, thank you so much.

[Jilan Samiuddin]

perfect!

Answer 2

[Ned Gulley]

It looks like you've got a symbolic expression.

You can substitute real numeric values for x1 and x2 like this:

% Define your expression
syms x1 x2
f = (3060513257434037*x1^2)/1125899906842624 + x1 + ...
(3060513257434037*x2^2)/1125899906842624 + x2 + ...
 4186413164276661/1125899906842624;

% If x1 is 1 and x2 is 2, you would type this
subs(f,{x1,x2},{1,2})

And the answer is...

ans =
  20.3097

See the doc for subs for more information.

Answer 3

[kalpana]

use MatlabFunction() to convert symbolic to numeric expression.