281 lines
5.6 KiB
HTML
281 lines
5.6 KiB
HTML
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<!DOCTYPE HTML>
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<HTML LANG="en-us"
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>abs | Common Lisp Nova Spec</TITLE
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><A HREF="index.html"
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>Common Lisp Nova Spec</A
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></SPAN
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> <SPAN CLASS="breadcrumb-item"
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>→ <A HREF="12_Numbers.html"
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>12. Numbers</A
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> <SPAN CLASS="breadcrumb-item"
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>→ <A HREF="12_2_Numbers_Dictionary.html"
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>12.2 Numbers Dictionary</A
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>abs</A
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>←</A
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>Apropos </SPAN
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><INPUT ID="apropos" AUTOFOCUS="AUTOFOCUS" PLACEHOLDER="Type here to search" ONINPUT="aproposInput(this);" ONKEYUP="aproposKeyup(event);" ONCHANGE="aproposChange(this);" ONFOCUS="aproposFocus(this);" ONFOCUSOUT="aproposFocusout(this);"
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></DIV
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><DIV CLASS="matter"
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><DIV CLASS="com"
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><DIV CLASS="begincom"
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><HR
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><TABLE WIDTH="100%" CELLSPACING="0" CELLPADDING="0"
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><TR
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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="abs"
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></SPAN
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><B
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>abs</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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>Function</I
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></TD
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></TR
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></TABLE
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><HR
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></DIV
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><UL CLASS="subtoc"
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></UL
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><DL
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><DT
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><B
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>Syntax</B
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></DT
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><DD
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><P CLASS="j"
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><B
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>abs</B
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> <SPAN CLASS="cmssi"
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>number</SPAN
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> <SPAN CLASS="arrow"
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>→</SPAN
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> <SPAN CLASS="cmssi"
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>absolute-value</SPAN
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></P
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></DD
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><DT
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><B
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>Arguments and Values</B
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></DT
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><DD
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><P CLASS="j"
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><VAR CLASS="param"
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>number</VAR
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> — a <A HREF="26_1_Glossary.html#number"
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><EM CLASS="term"
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>number</EM
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></A
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>. </P
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><P CLASS="j"
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><VAR CLASS="param"
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>absolute-value</VAR
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> — a non-negative <EM CLASS="term"
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>real</EM
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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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><A HREF="f_abs.html" CLASS="funref"
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><B
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>abs</B
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></A
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> returns the absolute value of <VAR CLASS="param"
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>number</VAR
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>. </P
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><P CLASS="j"
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>If <VAR CLASS="param"
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>number</VAR
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> is a <EM CLASS="term"
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>real</EM
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>, the result is of the same <A HREF="26_1_Glossary.html#type"
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><EM CLASS="term"
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>type</EM
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></A
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> as <VAR CLASS="param"
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>number</VAR
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>. </P
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><P CLASS="j"
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>If <VAR CLASS="param"
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>number</VAR
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> is a <A HREF="26_1_Glossary.html#complex"
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><EM CLASS="term"
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>complex</EM
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></A
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>, the result is a positive <EM CLASS="term"
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>real</EM
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> with the same magnitude as <VAR CLASS="param"
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>number</VAR
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>. The result can be 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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> even if <VAR CLASS="param"
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>number</VAR
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>’s components are <A HREF="26_1_Glossary.html#rational"
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><EM CLASS="term"
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>rationals</EM
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></A
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> and an exact rational result would have been possible. Thus the result of <CODE CLASS="f"
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>(abs #c(3 4))</CODE
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> can be either <CODE CLASS="f"
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>5</CODE
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> or <CODE CLASS="f"
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>5.0</CODE
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>, depending on the implementation.</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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>(abs 0) <SPAN CLASS="cmsy"
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><SPAN CLASS="arrow"
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>→</SPAN
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></SPAN
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> 0
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(abs 12/13) <SPAN CLASS="cmsy"
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><SPAN CLASS="arrow"
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>→</SPAN
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></SPAN
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> 12/13
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(abs -1.09) <SPAN CLASS="cmsy"
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><SPAN CLASS="arrow"
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>→</SPAN
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></SPAN
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> 1.09
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(abs #c(5.0 -5.0)) <SPAN CLASS="cmsy"
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><SPAN CLASS="arrow"
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>→</SPAN
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></SPAN
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> 7.071068
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(abs #c(5 5)) <SPAN CLASS="cmsy"
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><SPAN CLASS="arrow"
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>→</SPAN
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></SPAN
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> 7.071068
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(abs #c(3/5 4/5)) <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 or approximately 1.0
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(eql (abs -0.0) -0.0) <SPAN CLASS="cmsy"
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><SPAN CLASS="arrow"
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>→</SPAN
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></SPAN
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> <A HREF="26_1_Glossary.html#true"
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><EM CLASS="term"
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>true</EM
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></A
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></PRE
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></DD
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><DT
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><B
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>See Also</B
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></DT
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><DD
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><P CLASS="j"
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><A HREF="12_1_Number_Concepts.html#sec_12_1_3_3" CLASS="secref"
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><SPAN CLASS="cmr"
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>Section</SPAN
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> <SPAN CLASS="cmr"
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>12.1.3.3</SPAN
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> <SPAN CLASS="cmr"
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>(Rule</SPAN
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> <SPAN CLASS="cmr"
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>of</SPAN
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> <SPAN CLASS="cmr"
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>Float</SPAN
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> <SPAN CLASS="cmr"
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>Substitutability)</SPAN
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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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>Notes</B
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></DT
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><DD
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><P CLASS="j"
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>If <VAR CLASS="param"
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>number</VAR
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> is a <A HREF="26_1_Glossary.html#complex"
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><EM CLASS="term"
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>complex</EM
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></A
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>, the result is equivalent to the following: </P
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><P CLASS="j"
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><CODE CLASS="f"
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>(sqrt (+ (expt (realpart <VAR CLASS="param"
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>number</VAR
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>) 2) (expt (imagpart <VAR CLASS="param"
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>number</VAR
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>) 2)))</CODE
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> </P
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><P CLASS="j"
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>An implementation should not use this formula directly for all <A HREF="26_1_Glossary.html#complex"
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><EM CLASS="term"
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>complexes</EM
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></A
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> but should handle very large or very small components specially to avoid intermediate overflow or underflow.</P
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></DD
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></DL
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></DIV
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></DIV
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><DIV CLASS="footer"
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><DIV CLASS="btmnav"
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><A HREF="f_1_plus.html" CLASS="prev"
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>←</A
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><A HREF="f_evenp.html" CLASS="next"
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>→</A
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></DIV
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><DIV CLASS="trail"
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>Conversion to HTML copyright 2023 by Gilbert Baumann</DIV
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></DIV
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></DIV
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><SCRIPT
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>domReady();</SCRIPT
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></BODY
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>
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