We don't usually use a rule of commonly used names in PH, but names that follow our coding standards. Personally, I also don't think std_dev is that common that everyone knows what it stands for (although they can guess). I don't bump into std_dev on a yearly basis even.
I agree with Jani that making this math_standard_deviation() would be better, especially as it's not likely to be widely used so typing a few extra chars shouldn't be a hassle (at least it isn't for me, but I type quickly).
Andi
At 02:34 PM 5/10/2005 +0300, [EMAIL PROTECTED] wrote:
Hi Andi, you are lagging 10 days :) What problem do you find with math_std_dev() ? As far as I know std_dev is the commonly used name for standard deviation.
andrey
Quoting Andi Gutmans <[EMAIL PROTECTED]>:
Damn right! :)
At 01:37 PM 5/2/2005 +0300, Jani Taskinen wrote:
Why the cryptic name? Why not math_standard_deviation() ? And I'm pretty sure Andi will ask the same soon.. :)
--Jani
On Mon, 2 May 2005, Andrey Hristov wrote:
andrey Mon May 2 05:17:50 2005 EDT
Added files: /php-src/ext/standard/tests/math math_std_dev.phpt
Modified files: /php-src/ext/standard basic_functions.c math.c php_math.h Log: add math_std_dev()
http://cvs.php.net/diff.php/php-src/ext/standard/basic_functions.c?r1=1.711&r2=1.712&ty=u
Index: php-src/ext/standard/basic_functions.c
diff -u php-src/ext/standard/basic_functions.c:1.711 php-src/ext/standard/basic_functions.c:1.712
--- php-src/ext/standard/basic_functions.c:1.711 Wed Apr 27 11:45:36 2005
+++ php-src/ext/standard/basic_functions.c Mon May 2 05:17:49 2005
@@ -17,7 +17,7 @@
+----------------------------------------------------------------------+ */
-/* $Id: basic_functions.c,v 1.711 2005/04/27 15:45:36 dmitry Exp $ */ +/* $Id: basic_functions.c,v 1.712 2005/05/02 09:17:49 andrey Exp $ */
#include "php.h" #include "php_streams.h" @@ -415,6 +415,7 @@ PHP_FE(base_convert, NULL) PHP_FE(number_format, NULL) PHP_FE(fmod, NULL) + PHP_FE(math_std_dev, NULL) #ifdef HAVE_INET_NTOP PHP_NAMED_FE(inet_ntop, php_inet_ntop, NULL) #endif http://cvs.php.net/diff.php/php-src/ext/standard/math.c?r1=1.119&r2=1.120&ty=u Index: php-src/ext/standard/math.c diff -u php-src/ext/standard/math.c:1.119 php-src/ext/standard/math.c:1.120 --- php-src/ext/standard/math.c:1.119 Mon Dec 13 19:37:19 2004 +++ php-src/ext/standard/math.c Mon May 2 05:17:49 2005 @@ -19,7 +19,7 @@
+----------------------------------------------------------------------+ */
-/* $Id: math.c,v 1.119 2004/12/14 00:37:19 iliaa Exp $ */ +/* $Id: math.c,v 1.120 2005/05/02 09:17:49 andrey Exp $ */
#include "php.h" #include "php_math.h" @@ -1182,6 +1182,40 @@ } /* }}} */
+
+
+/* {{{ proto float math_std_dev(array a)
+ Returns the standard deviation */
+PHP_FUNCTION(math_std_dev)
+{
+ double mean, sum = 0.0, vr = 0.0;
+ zval *arr, **entry;
+ HashPosition pos;
+
+ if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "a",
&arr) == FAILURE) {
+ return;
+ }
+ zend_hash_internal_pointer_reset_ex(Z_ARRVAL_P(arr), &pos);
+ while (zend_hash_get_current_data_ex(Z_ARRVAL_P(arr), (void **)&entry, &pos) == SUCCESS) {
+ convert_to_double_ex(entry);
+ sum += Z_DVAL_PP(entry);
+ zend_hash_move_forward_ex(Z_ARRVAL_P(arr), &pos);
+ }
+ mean = sum / zend_hash_num_elements(Z_ARRVAL_P(arr));
+
+ zend_hash_internal_pointer_reset_ex(Z_ARRVAL_P(arr), &pos);
+ while (zend_hash_get_current_data_ex(Z_ARRVAL_P(arr), (void **)&entry, &pos) == SUCCESS) {
+ double d;
+ convert_to_double_ex(entry);
+ d = Z_DVAL_PP(entry) - mean;
+ vr += d*d;
+ zend_hash_move_forward_ex(Z_ARRVAL_P(arr), &pos);
+ }
+
+ RETURN_DOUBLE(sqrt(vr / zend_hash_num_elements(Z_ARRVAL_P(arr))));
+}
+/* }}} */
+
/*
* Local variables:
* tab-width: 4
http://cvs.php.net/diff.php/php-src/ext/standard/php_math.h?r1=1.23&r2=1.24&ty=u
Index: php-src/ext/standard/php_math.h
diff -u php-src/ext/standard/php_math.h:1.23 php-src/ext/standard/php_math.h:1.24
--- php-src/ext/standard/php_math.h:1.23 Tue Sep 21 14:09:29 2004
+++ php-src/ext/standard/php_math.h Mon May 2 05:17:49 2005
@@ -17,7 +17,7 @@
+----------------------------------------------------------------------+ */
-/* $Id: php_math.h,v 1.23 2004/09/21 18:09:29 fmk Exp $ */ +/* $Id: php_math.h,v 1.24 2005/05/02 09:17:49 andrey Exp $ */
#ifndef PHP_MATH_H #define PHP_MATH_H @@ -59,6 +59,7 @@ PHP_FUNCTION(base_convert); PHP_FUNCTION(number_format); PHP_FUNCTION(fmod); +PHP_FUNCTION(math_std_dev); PHP_FUNCTION(deg2rad); PHP_FUNCTION(rad2deg);
http://cvs.php.net/co.php/php-src/ext/standard/tests/math/math_std_dev.phpt?r=1.1&p=1 Index: php-src/ext/standard/tests/math/math_std_dev.phpt +++ php-src/ext/standard/tests/math/math_std_dev.phpt --TEST-- math_std_dev() tests --FILE-- <?php $a=array(4, 1, 7); $dev=math_std_dev($a); var_dump(sprintf("%2.9f", $dev)); ?> --EXPECT-- string(11) "2.449489743"
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