Math.PI.toString(16) -> 3.243f6a8885a3 and back
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From: Dr J R Stockton on 26 May 2010 16:44 Some may not have noted that Number.toString(16) handles non-integers. Math.PI.toString(16) -> 3.243f6a8885a3 1e44.toString(16) -> 47bf19673df53000000000000000000000000 Math.random().toString(2) => 0 . /[01]{1,53}/ ECMA 262 (5) 15.7.4.2 Number.prototype.toString ( [ radix ] ) makes no mention of non-integers. A Hex integer string H can be turned into a Number by + ( "0x" + H ) but that does not work for a Hex fraction string. Is there in fact an easy built-in way of converting non-integer Hex strings to Number? Otherwise, I suggest that ECMA 6 should specify a Method whereby for ANY Number X the result of X.toString(B) can be converted to the original X (disregarding the sign of zero). -- (c) John Stockton, nr London UK. ?@merlyn.demon.co.uk Turnpike v6.05 MIME. Grandson-Of-RFC1036 is released. RFC 5536 Netnews Article Format is a subset of Internet Message Format which is described in RFC 5532. The RFCs are read together to determine standard Netnews article format.
From: Ry Nohryb on 26 May 2010 19:14 On May 26, 10:44 pm, Dr J R Stockton <reply1...(a)merlyn.demon.co.uk> wrote: > Some may not have noted that Number.toString(16) handles non-integers. > Math.PI.toString(16) -> 3.243f6a8885a3 > 1e44.toString(16) -> 47bf19673df53000000000000000000000000 > Math.random().toString(2) => 0 . /[01]{1,53}/ My dear friend Garrett and I know that at least since: http://groups.google.com/group/comp.lang.javascript/msg/936a683de6159fd0 > ECMA 262 (5) 15.7.4.2 Number.prototype.toString ( [ radix ] ) > makes no mention of non-integers. > > A Hex integer string H can be turned into a Number by > + ( "0x" + H ) > but that does not work for a Hex fraction string. Is there in fact an > easy built-in way of converting non-integer Hex strings to Number? a= 113356057.78731406 --> 113356057.78731406 b= a.toString(16).split('.'); --> [ "6c1ad19", "c98d6a" ] c= +( '0x'+ b.join('') ) / Math.pow(16, b[1].length) --> 113356057.78731406 > Otherwise, I suggest that ECMA 6 should specify a Method whereby for ANY > Number X the result of X.toString(B) can be converted to the original X > (disregarding the sign of zero). -- Jorge.
From: Evertjan. on 27 May 2010 05:11 Ry Nohryb wrote on 27 mei 2010 in comp.lang.javascript: > a= 113356057.78731406 > --> 113356057.78731406 > > b= a.toString(16).split('.'); > --> [ "6c1ad19", "c98d6a" ] > > c= +( '0x'+ b.join('') ) / Math.pow(16, b[1].length) > --> 113356057.78731406 or just add the fractional part to the integer part. =========================================== Try this for any radix [0 .. 36]: <script type='text/javascript'> document.write(radixTo10('6c1ad19.c98d6a',16) + '<br>') // --> 113356057.78731406 document.write(radixTo10('778',8) + '<br>') // --> 511 document.write(radixTo10('z',36) + '<br>') // --> 35 document.write(radixTo10('10',36) + '<br>') // --> 36 function radixTo10int(v,radix) { var n = 0; for (i=0;i<v.length;i++) { temp = v[i]; temp = (temp>'9') ? 10+temp.charCodeAt(0)-'a'.charCodeAt(0) : +temp; //if (temp>radix-1) return 'error'; n *= radix; n += temp; }; return n; }; function radixTo10(v,radix) { v = v.toLowerCase().split('.'); if (v.length==1) return radixTo10int(v[0],radix); return radixTo10int(v[0],radix) + radixTo10int(v[1],radix) / Math.pow(radix,v[1].length); }; </script> -- Evertjan. The Netherlands. (Please change the x'es to dots in my emailaddress)
From: Evertjan. on 27 May 2010 05:16 Evertjan. wrote on 27 mei 2010 in comp.lang.javascript: > Ry Nohryb wrote on 27 mei 2010 in comp.lang.javascript: > >> a= 113356057.78731406 >> --> 113356057.78731406 >> >> b= a.toString(16).split('.'); >> --> [ "6c1ad19", "c98d6a" ] >> >> c= +( '0x'+ b.join('') ) / Math.pow(16, b[1].length) >> --> 113356057.78731406 > > or just add the fractional part to the integer part. > > =========================================== > > Try this for any radix [0 .. 36]: > > <script type='text/javascript'> > > document.write(radixTo10('6c1ad19.c98d6a',16) + '<br>') > // --> 113356057.78731406 > document.write(radixTo10('778',8) + '<br>') > // --> 511 sorry: document.write(radixTo10('777',8) + '<br>') // --> 511 > document.write(radixTo10('z',36) + '<br>') > // --> 35 > document.write(radixTo10('10',36) + '<br>') > // --> 36 > > > function radixTo10int(v,radix) { > var n = 0; > for (i=0;i<v.length;i++) { > temp = v[i]; > temp = (temp>'9') > ? 10+temp.charCodeAt(0)-'a'.charCodeAt(0) > : +temp; > //if (temp>radix-1) return 'error'; > n *= radix; > n += temp; > }; > return n; >}; > > function radixTo10(v,radix) { > v = v.toLowerCase().split('.'); > if (v.length==1) > return radixTo10int(v[0],radix); > return radixTo10int(v[0],radix) + > radixTo10int(v[1],radix) / Math.pow(radix,v[1].length); >}; > > </script> > > -- Evertjan. The Netherlands. (Please change the x'es to dots in my emailaddress)
From: Ry Nohryb on 27 May 2010 07:56
On May 27, 11:11 am, "Evertjan." <exjxw.hannivo...(a)interxnl.net> wrote: > Ry Nohryb wrote on 27 mei 2010 in comp.lang.javascript: > > > a= 113356057.78731406 > > --> 113356057.78731406 > > > b= a.toString(16).split('.'); > > --> [ "6c1ad19", "c98d6a" ] > > > c= +( '0x'+ b.join('') ) / Math.pow(16, b[1].length) > > --> 113356057.78731406 > > or just add the fractional part to the integer part. > > =========================================== > > Try this for any radix [0 .. 36]: > > <script type='text/javascript'> > > document.write(radixTo10('6c1ad19.c98d6a',16) + '<br>') > // --> 113356057.78731406 > document.write(radixTo10('778',8) + '<br>') > // --> 511 > document.write(radixTo10('z',36) + '<br>') > // --> 35 > document.write(radixTo10('10',36) + '<br>') > // --> 36 > > function radixTo10int(v,radix) { > var n = 0; > for (i=0;i<v.length;i++) { > temp = v[i]; > temp = (temp>'9') > ? 10+temp.charCodeAt(0)-'a'.charCodeAt(0) > : +temp; > //if (temp>radix-1) return 'error'; > n *= radix; > n += temp; > }; > return n; > > }; > > function radixTo10(v,radix) { > v = v.toLowerCase().split('.'); > if (v.length==1) > return radixTo10int(v[0],radix); > return radixTo10int(v[0],radix) + > radixTo10int(v[1],radix) / Math.pow(radix,v[1].length); > > }; > > </script> Cute. How about this one :-) ? String.prototype.toFP= function (base, digits, r, w, n) { digits= "0123456789abcdefghijklmnopqrstuvwxyz", r= 0; w= (n= this.toLowerCase().split('.'))[0].length; n.join('').split('').forEach(function (s) { r+= digits.indexOf(s) * Math.pow(base, --w) }); return r; }; a= Math.PI --> 3.141592653589793 b= a.toString(16) --> "3.243f6a8885a3" a.toFP(16) --> 3.141592653589793 b= a.toString(36) --> "3.53i5ab8p5fc5vayqter60f6r" b.toFP(36) --> 3.141592653589793 b= a.toString(2) --> "11.001001000011111101101010100010001000010110100011" b.toFP(2) --> 3.141592653589793 -- Jorge. |