Symbolic Math Toolbox

Another Example

The next example is perhaps more interesting. Start with the symbolic expression

• f = sym('exp(pi*sqrt(163))')
  

The statement

• double(f)
  

produces the printed floating-point value

• 2.625374126407687e+17
  

Using the second argument of vpa to specify the number of digits,

• vpa(f,18)
  

returns

• 262537412640768744.
  

whereas

• vpa(f,25)
  

returns

• 262537412640768744.0000000
  

We suspect that f might actually have an integer value. This suspicion is reinforced by the 30 digit value, vpa(f,30)

• 262537412640768743.999999999999
  

Finally, the 40 digit value, vpa(f,40)

• 262537412640768743.9999999999992500725944
  

shows that f is very close to, but not exactly equal to, an integer.

Example: Using the Different Kinds of Arithmetic

Linear Algebra