devdocs/elisp/floating_002dpoint-type.html


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 <h4 class="subsection">Floating-Point Type</h4> <p>Floating-point numbers are the computer equivalent of scientific notation; you can think of a floating-point number as a fraction together with a power of ten. The precise number of significant figures and the range of possible exponents is machine-specific; Emacs uses the C data type <code>double</code> to store the value, and internally this records a power of 2 rather than a power of 10. </p> <p>The printed representation for floating-point numbers requires either a decimal point (with at least one digit following), an exponent, or both. For example, ‘<samp>1500.0</samp>’, ‘<samp>+15e2</samp>’, ‘<samp>15.0e+2</samp>’, ‘<samp>+1500000e-3</samp>’, and ‘<samp>.15e4</samp>’ are five ways of writing a floating-point number whose value is 1500. They are all equivalent. </p> <p>See <a href="numbers">Numbers</a>, for more information. </p><div class="_attribution">
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