MATLAB Programming Fundamentals - MathWorks

Infinity and NaN

In this section...

“Infinity” on page 4-18

“NaN” on page 4-18

Infinity

MATLAB represents infinity by the special value inf. Infinity results from operations like

division by zero and overflow, which lead to results too large to represent as conventional

floating-point values. MATLAB also provides a function called inf that returns the IEEE

arithmetic representation for positive infinity as a double scalar value.

Several examples of statements that return positive or negative infinity in MATLAB are

shown here.

x = 1/0

x =

Inf

x = 1.e1000

x =

Inf

x = exp(1000)

x =

Inf

x = log(0)

x =

-Inf

Use the isinf function to verify that x is positive or negative infinity:

x = log(0);

isinf(x)

ans =

1

NaN

MATLAB represents values that are not real or complex numbers with a special value

called NaN, which stands for “Not a Number”. Expressions like 0/0 and inf/inf result in

NaN, as do any arithmetic operations involving a NaN:

x = 0/0

x =

4 Numeric Classes