1<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"> 2 3<!--Converted with LaTeX2HTML 2018.3 (Released July 19, 2018) --> 4<HTML lang="EN"> 5<HEAD> 6<TITLE>npix2nside</TITLE> 7<META NAME="description" CONTENT="npix2nside"> 8<META NAME="keywords" CONTENT="csub"> 9<META NAME="resource-type" CONTENT="document"> 10<META NAME="distribution" CONTENT="global"> 11 12<META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=utf-8"> 13<META NAME="viewport" CONTENT="width=device-width, initial-scale=1.0"> 14<META NAME="Generator" CONTENT="LaTeX2HTML v2018.3"> 15 <link rel='apple-touch-icon' sizes='180x180' href='images/favicons/apple-touch-icon.png?v=2017'> 16 <link rel='icon' type='image/png' sizes='32x32' href='images/favicons/favicon-32x32.png?v=2017'> 17 <link rel='icon' type='image/png' sizes='16x16' href='images/favicons/favicon-16x16.png?v=2017'> 18 <link rel='manifest' href='images/favicons/manifest.json?v=2017'> 19 <link rel='mask-icon' href='images/favicons/safari-pinned-tab.svg?v=2017' color='#5bbad5'> 20 <link rel='shortcut icon' href='images/favicons/favicon.ico?v=2017'> 21 <meta name='apple-mobile-web-app-title' content='HEALPix'> 22 <meta name='application-name' content='HEALPix'> 23 <meta name='msapplication-config' content='images/favicons/browserconfig.xml?v=2017'> 24 <meta name='theme-color' content='#ffffff'> 25 26<LINK REL="STYLESHEET" HREF="csub.css"> 27 28<LINK REL="next" HREF="csub_nside2npix.htm"> 29<LINK REL="previous" HREF="csub_get_fits_size.htm"> 30<LINK REL="next" HREF="csub_nside2npix.htm"> 31</HEAD> 32 33<body text="#000000" bgcolor="#FFFFFA"> 34 35<DIV CLASS="navigation"><!--Navigation Panel--> 36<A 37 HREF="csub_get_fits_size.htm"> 38<IMG WIDTH="63" HEIGHT="24" ALT="previous" SRC="prev.png"></A> 39<A 40 HREF="csub_HEALPix_C_subroutines.htm"> 41<IMG WIDTH="26" HEIGHT="24" ALT="up" SRC="up.png"></A> 42<A 43 HREF="csub_nside2npix.htm"> 44<IMG WIDTH="37" HEIGHT="24" ALT="next" SRC="next.png"></A> 45<A ID="tex2html44" 46 HREF="csub_Contents.htm"> 47<IMG WIDTH="65" HEIGHT="24" ALT="contents" SRC="contents.png"></A> 48<BR> 49<B> Previous:</B> <A 50 HREF="csub_get_fits_size.htm">get_fits_size</A> 51 52<B>Up:</B> <A 53 HREF="csub_HEALPix_C_subroutines.htm">HEALPix/C subroutines</A> 54 55<B> Next:</B> <A 56 HREF="csub_nside2npix.htm">nside2npix</A> 57<B> Top:</B> <a href="main.htm">Main Page</a></DIV> 58<!--End of Navigation Panel--> 59 60<H1><A ID="SECTION800"></A> 61<A ID="csub:npix2nside"></A> 62<BR> 63 64</H1> 65 66<P> 67<b><font size=+6><FONT COLOR="#CC0000">npix2nside</FONT></font></b><hr> 68<H3>Function to provide the resolution parameter <!-- MATH 69 $N_{\mathrm{side}}$ 70 --> 71<SPAN CLASS="MATH"><I>N</I><SUB>side</SUB></SPAN> corresponding to the number of pixels <!-- MATH 72 $N_{\mathrm{pix}}$ 73 --> 74<SPAN CLASS="MATH"><I>N</I><SUB>pix</SUB></SPAN> over the full sky. 75</H3> 76Location in HEALPix directory tree: <a href="https://sourceforge.net/p/healpix/code/1005/tree/trunk/src/C/subs/chealpix.c"><b>src/C/subs/chealpix.c</b></a> 77 78<P> 79<hr><h1>FORMAT </h1><h3> 80long npix2nside(const long npix) 81</h3> 82 83<P> 84<hr><H1>ARGUMENTS</H1> 85 86<TABLE CELLPADDING=3 BORDER="1"> 87<TR><TH ALIGN="LEFT" VALIGN="TOP" WIDTH=150><SPAN CLASS="textbf">name&dimensionality</SPAN></TH> 88<TH ALIGN="LEFT" VALIGN="TOP" WIDTH=25><SPAN CLASS="textbf">kind</SPAN></TH> 89<TH ALIGN="LEFT" VALIGN="TOP" WIDTH=50><SPAN CLASS="textbf">in/out</SPAN></TH> 90<TH ALIGN="LEFT" VALIGN="TOP" WIDTH=225><SPAN CLASS="textbf">description</SPAN></TH> 91</TR> 92<TR><TD ALIGN="LEFT" VALIGN="TOP" WIDTH=150> </TD> 93<TD ALIGN="LEFT" VALIGN="TOP" WIDTH=25> </TD> 94<TD ALIGN="LEFT" VALIGN="TOP" WIDTH=50> </TD> 95<TD ALIGN="LEFT" VALIGN="TOP" WIDTH=225> </TD> 96</TR> 97<TR><TD ALIGN="LEFT" VALIGN="TOP" WIDTH=150> 98npix</TD> 99<TD ALIGN="LEFT" VALIGN="TOP" WIDTH=25>long</TD> 100<TD ALIGN="LEFT" VALIGN="TOP" WIDTH=50>IN</TD> 101<TD ALIGN="LEFT" VALIGN="TOP" WIDTH=225>the number of pixels <!-- MATH 102 $N_{\mathrm{pix}}$ 103 --> 104<SPAN CLASS="MATH"><I>N</I><SUB>pix</SUB></SPAN> of the map .</TD> 105</TR> 106<TR><TD ALIGN="LEFT" VALIGN="TOP" WIDTH=150><FONT COLOR="#CC0000">npix2nside</FONT></TD> 107<TD ALIGN="LEFT" VALIGN="TOP" WIDTH=25>long</TD> 108<TD ALIGN="LEFT" VALIGN="TOP" WIDTH=50>OUT</TD> 109<TD ALIGN="LEFT" VALIGN="TOP" WIDTH=225>returns the <!-- MATH 110 $N_{\mathrm{side}}$ 111 --> 112<SPAN CLASS="MATH"><I>N</I><SUB>side</SUB></SPAN> parameter of the map such that <!-- MATH 113 $N_{\mathrm{pix}}=12N_{\mathrm{side}}^2$ 114 --> 115<SPAN CLASS="MATH"><I>N</I><SUB>pix</SUB>=12<I>N</I><SUB>side</SUB><SUP><i>2</i></SUP></SPAN>.</TD> 116</TR> 117</TABLE> 118 119<P> 120<HR><H1>EXAMPLE:</H1> 121<tt>nside= npix2nside(786432); 122<BR></tt> 123<blockquote> 124Returns the resolution parameter (256) corresponding to 786432 <b>HEALPix</b> pixels. 125</blockquote> 126 127<P> 128<hr><H1>RELATED ROUTINES</H1><h3>This section lists the routines related to <b><FONT COLOR="#CC0000">npix2nside</FONT></b></h3> 129 130 <DL COMPACT><DT> 131<B><A HREF="csub_ang2vec.htm#csub:ang2vec">ang2vec</A></B> 132<DD>converts <SPAN CLASS="MATH"><IMG STYLE="height: 2.33ex; vertical-align: -0.68ex; " SRC="csub_img5.png" 133 ALT="$(\theta,\phi) $"></SPAN> spherical coordinates into <SPAN CLASS="MATH">(<I>x</I>,<I>y</I>,<I>z</I>)</SPAN> cartesian coordinates. 134 <DT> 135<B><A HREF="csub_vec2ang.htm#csub:vec2ang">vec2ang</A></B> 136<DD>converts <SPAN CLASS="MATH">(<I>x</I>,<I>y</I>,<I>z</I>)</SPAN> cartesian coordinates into <SPAN CLASS="MATH"><IMG STYLE="height: 2.33ex; vertical-align: -0.68ex; " SRC="csub_img5.png" 137 ALT="$(\theta,\phi) $"></SPAN> spherical coordinates. 138 <DT> 139<B><A HREF="csub_nside2npix.htm#csub:nside2npix">nside2npix</A></B> 140<DD>converts number of full sky pixels <!-- MATH 141 $N_{\mathrm{pix}}$ 142 --> 143<SPAN CLASS="MATH"><I>N</I><SUB>pix</SUB></SPAN> into resolution parameter <!-- MATH 144 $N_{\mathrm{side}}$ 145 --> 146<SPAN CLASS="MATH"><I>N</I><SUB>side</SUB></SPAN></DL> 147 148<P> 149 150 151<P> 152 153<P> 154 155<DIV CLASS="navigation"><HR> 156<!--Navigation Panel--> 157<A 158 HREF="csub_get_fits_size.htm"> 159<IMG WIDTH="63" HEIGHT="24" ALT="previous" SRC="prev.png"></A> 160<A 161 HREF="csub_HEALPix_C_subroutines.htm"> 162<IMG WIDTH="26" HEIGHT="24" ALT="up" SRC="up.png"></A> 163<A 164 HREF="csub_nside2npix.htm"> 165<IMG WIDTH="37" HEIGHT="24" ALT="next" SRC="next.png"></A> 166<A ID="tex2html44" 167 HREF="csub_Contents.htm"> 168<IMG WIDTH="65" HEIGHT="24" ALT="contents" SRC="contents.png"></A> 169<BR> 170<B> Previous:</B> <A 171 HREF="csub_get_fits_size.htm">get_fits_size</A> 172 173<B>Up:</B> <A 174 HREF="csub_HEALPix_C_subroutines.htm">HEALPix/C subroutines</A> 175 176<B> Next:</B> <A 177 HREF="csub_nside2npix.htm">nside2npix</A> 178<B> Top:</B> <a href="main.htm">Main Page</a></DIV> 179<!--End of Navigation Panel--> 180<ADDRESS> 181Version 3.50, 2018-12-10 182</ADDRESS> 183</BODY> 184</HTML> 185
