✨ feat(cmp): Add more efficient cmp.

Works when working with arbitrary precision integers.

Author: make-github-pseudonymous-again

src/cmp_no_bounds.js

@@ -0,0 +1,26 @@
+export function _cmp_no_bounds ( { jz , lt0 , mul , cmp } ) {
+	return function (a,b,c,d) {
+		if (jz(b)) {
+			if(lt0(a)) {
+				// a/b = -Infinity
+				return jz(d) ? lt0(c) ?
+					 0 : // b/d = -Infinity
+					-1 : // b/d = Infinity
+					-1 ; // b/d is finite
+			}
+			else {
+				// a/b = Infinity
+				return jz(d) ? lt0(c) ?
+					 1 : // b/d = -Infinity
+					 0 : // b/d = Infinity
+					 1 ; // b/d is finite
+			}
+		}
+		// a/b is finite
+		if (jz(d)) return lt0(c) ?
+			 1 : // b/d = -Infinity
+			-1 ; // b/d = Infinity
+
+		return cmp(mul(a,d), mul(b,c)) ;
+	} ;
+}

src/index.js

@@ -3,3 +3,4 @@ export * from './div' ;
 export * from './mul' ;
 export * from './sub' ;
 export * from './cmp' ;
+export * from './cmp_no_bounds' ;

test/src/core.js

@@ -1,12 +1,12 @@
 import test from 'ava';
-import { _add , _sub , _mul , _div , _cmp } from '../../src';
+import { _add , _sub , _mul , _div , _cmp , _cmp_no_bounds } from '../../src';
 
 import int from 'int' ;
 import { ZZ } from '@aureooms/js-integer' ;
 
 const GOOGOL = '10000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000' ;
 
-function macro ( t , alu , [ [ _x , _y , _z , factory ] , a , b , c , d , e ] ) {
+function macro ( t , alu , [ [ _x , _y , factory ] , a , b , c , d , e ] ) {
 
 	const apply = factory( alu );
 
@@ -26,7 +26,7 @@ function macro ( t , alu , [ [ _x , _y , _z , factory ] , a , b , c , d , e ] )
 }
 
 macro.title = ( _ , alu , [ [ name , op , impl ] , a , b , c , d , e] ) => {
-	return `${name}<${impl}, ${alu.name}> ${a}/${b} ${op} ${c}/${d} = ${e}` ;
+	return `${name}<${impl.name}, ${alu.name}> ${a}/${b} ${op} ${c}/${d} = ${e}` ;
 } ;
 
 const ALU = [
@@ -60,11 +60,11 @@ const ALU = [
 	}
 ];
 
-const add = [ 'add' , '+' , '_add' , alu => _add( alu ) ] ;
-const sub = [ 'sub' , '-' , '_sub' , alu => _sub( alu ) ] ;
-const mul = [ 'mul' , '*' , '_mul' , alu => _mul( alu ) ] ;
-const div = [ 'div' , '/' , '_div' , alu => _div( alu ) ] ;
-const cmp = [ 'cmp' , '~' , '_cmp' , alu => _cmp( alu ) ] ;
+const add = [ 'add' , '+' , [ _add ] ] ;
+const sub = [ 'sub' , '-' , [ _sub ] ] ;
+const mul = [ 'mul' , '*' , [ _mul ] ] ;
+const div = [ 'div' , '/' , [ _div ] ] ;
+const cmp = [ 'cmp' , '~' , [ _cmp , _cmp_no_bounds ] ] ;
 
 const PARAMS = [
 
@@ -134,5 +134,6 @@ const PARAMS = [
 ] ;
 
 for (const alu of ALU)
-for (const params of PARAMS)
-	test(macro, alu, params);
+for (const [[name, symbol, implementations], ...params] of PARAMS)
+for (const factory of implementations)
+	test(macro, alu, [[name, symbol, factory], ...params]);