subtraction

Basically, the behavior you get when overflowing integers with subtraction, but for a given number of bits. The obvious way, assuming a signed integer: template <int BITS> int sub_wrap(int v, int s) { int max = (1<<(BITS)); v -= s; if (v < -max) v += max*2; // or if branching is bad, something like: // v += (max*2) * (v < -max) return v; } // For example subtracting 24 from -16 with 5 bit wrap, // with a range of -32, 31 sub_wrap<5>(-16, 28); -> 20 Is there a neat way of doing it that is less ugly and preferably faster than the one above? UPDATE: Sorry about the confusion. I thoughtlessly

I need to declare two dates in "Ymd" format: $toDate and $fromDate . $toDate represents today's date and $fromDate needs to be 4 months earlier than today. $toDate = Date('Ymd'); $fromDate = ? How do I create $fromDate ? Use the magic of strtotime : $fromDate = date("Ymd", strtotime("-4 months")); see the code below... $fourmonthsback = date("Ymd", mktime(0, 0, 0, date("m")-4, date("d"), date("Y"))); OR $fourmonthsback = mktime(0, 0, 0, date("m")-4, date("d"), date("Y")); 来源： https://stackoverflow.com/questions/4163387/how-to-subtract-4-months-from-todays-date

So if today was April 12, 2010 it should return October 1, 2009 Some possible solutions I've googled seem overly complex, any suggestions? Hm, maybe something like this; echo date("F 1, Y", strtotime("-6 months")); EDIT; if you would like to specify a custom date use; echo date("F, 1 Y", strtotime("-6 months", strtotime("Feb 2, 2010"))); A bit hackish but works: <?php $date = new DateTime("-6 months"); $date->modify("-" . ($date->format('j')-1) . " days"); echo $date->format('j, F Y'); ?> use a combination of mktime and date : $date_half_a_year_ago = mktime(0, 0, 0, date('n')-6, 1, date('y'))

How can I subtract one image from another using openCV? Ps.: I coudn't use the python implementation because I'll have to do it in C++ Use LoadImage to load your images into memory, then use the Sub method. This link contains some example code, if that will help: http://permalink.gmane.org/gmane.comp.lib.opencv/36167 #include <cv.h> #include <highgui.h> using namespace cv; Mat im = imread("cameraman.tif"); Mat im2 = imread("lena.tif"); Mat diff_im = im - im2; Change the image names. Also make sure they have the same size. Instead of using diff or just plain subtraction im1-im2 I would rather

Is there a way to subtract the smallest value from all the values of a column? I need to subtract the first number in the 1st column from all other numbers in the first column. I wrote this script, but it's not giving the right result: $ awk '{$1 = $1 - 1280449530}' file 1280449530 452 1280449531 2434 1280449531 2681 1280449531 2946 1280449531 1626 1280449532 3217 1280449532 4764 1280449532 4501 1280449532 3372 1280449533 4129 1280449533 6937 1280449533 6423 1280449533 4818 1280449534 4850 1280449534 8980 1280449534 8078 1280449534 6788 1280449535 5587 1280449535 10879 1280449535 9920

I am trying to build up subtraction, addition, division, multiplication and other operations using only following ones: incr(x) - Once this function is called it will assign x + 1 to x assign(x, y) - This function will assign the value of y to x (x = y) zero(x) - This function will assign 0 to x (x = 0) loop X { } - operations written within brackets will be executed X times Using following rules it is straight forward to implement addition (add) like this: ADD (x, y) { loop X { y = incr (y) } return y } However, I'm struggling to implement subtraction . I think that all the other needed