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>pi | Common Lisp Nova Spec</TITLE
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><TABLE WIDTH="100%" CELLSPACING="0" CELLPADDING="0"
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><TD ALIGN="LEFT" VALIGN="BASELINE" WIDTH="100%" CLASS="name"
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><SPAN CLASS="idx" DATA-KIND="idxref" DATA-TERM="pi"
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><B
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>pi</B
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></TD
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><TD ALIGN="RIGHT" VALIGN="BASELINE" WIDTH="0" NOWRAP="NOWRAP" CLASS="ftype"
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><I
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>Constant</I
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> <I
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>Variable</I
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>Value</B
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></DT
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><DD
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><P CLASS="j"
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>an <A HREF="26_1_Glossary.html#implementation-dependent"
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><EM CLASS="term"
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>implementation-dependent</EM
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></A
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> <A HREF="26_1_Glossary.html#long_float"
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><EM CLASS="term"
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>long float</EM
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></A
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>.</P
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></DD
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><DT
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><B
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>Description</B
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></DT
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><DD
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><P CLASS="j"
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>The best <A HREF="26_1_Glossary.html#long_float"
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><EM CLASS="term"
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>long float</EM
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></A
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> approximation to the mathematical constant π.</P
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></DD
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><DT
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><B
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>Examples</B
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></DT
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><DD
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><PRE CLASS="screen"
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>;; In each of the following computations, the precision depends
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;; on the implementation. Also, if `long float' is treated by
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;; the implementation as equivalent to some other float format
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;; (e.g., `double float') the exponent marker might be the marker
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;; for that equivalent (e.g., `D' instead of `L').
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pi <SPAN CLASS="cmsy"
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><SPAN CLASS="arrow"
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>→</SPAN
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></SPAN
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> 3.141592653589793L0
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(cos pi) <SPAN CLASS="cmsy"
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><SPAN CLASS="arrow"
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>→</SPAN
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></SPAN
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> -1.0L0
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(defun sin-of-degrees (degrees)
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(let ((x (if (floatp degrees) degrees (float degrees pi))))
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(sin (* x (/ (float pi x) 180)))))</PRE
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></DD
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><DT
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><B
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>Notes</B
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></DT
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><DD
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><P CLASS="j"
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>An approximation to π in some other precision can be obtained by writing <CODE CLASS="f"
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>(float pi x)</CODE
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>, where <CODE CLASS="f"
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>x</CODE
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> is a <A HREF="26_1_Glossary.html#float"
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><EM CLASS="term"
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>float</EM
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></A
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> of the desired precision, or by writing <CODE CLASS="f"
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>(coerce pi <I CLASS="i"
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><I
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>type</I
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></I
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>)</CODE
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>, where <I CLASS="i"
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><I
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>type</I
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></I
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> is the desired type, such as <A HREF="t_short-float.html" CLASS="typeref"
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><B
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>short-float</B
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></A
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>.</P
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></DD
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>Conversion to HTML copyright 2023 by Gilbert Baumann</DIV
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