## Lens Design – What makes the Canon RF 70-200 f / 2.8 much smaller than the EF version?

It is possible to image with a modest single element lens. We are sorry to report that the resulting pictures are second-rate. This is because all the lenses have aberrations that deteriorate. Opticians mitigate aberrations by combining numerous lenses. Some are positive (convex) and others negative (concave) in terms of performance. In addition, some are cemented together; others are at air distances. It takes all this to mitigate deviations. However, residual errors always remain.

If the camera were equipped with a lens with a single element and focused on a distant perspective, we could take a measurement from the lens center to the image plane. This value is the focal length. In a complex lens array, finding the point for this measurement is less clear. The point we need to find is called the back node.

Opticians can and must move the position of the posterior node. Now a long lens is a long focal length. The longer the focal length, the larger the magnification. A long lens is very desirable if you are interested in sports, wildlife or the like. However, it may be that a long lens is a bit awkward.

Opticians have a trick on their sleeve that physically shortens the lens barrel. This is achieved by moving the rear node forward. If the optician so desires, a complex array of lens elements may be constructed so that the posterior node falls into the air in front of the anterior element.

Remember that the focal length is a measure measured from the back to the image plane. The advantage of such a design is a shorter, less cumbersome run length. Let me add: A real tele-design differs from the long lens in that the telephoto lens is shortened in terms of the run length.

You should also be aware that short wide-angle lenses often position the rear lens group too close to the image plane. If so, there is no room for the SLR mirror mechanism. The optician, who wants more space for the back focus removal, will move the rear knot backwards.

## Asymptotics – meaning of polynomial larger or smaller in the context of the master method

I'm studying the Master method to solve repetitions and have a decent mathematical background, but I'm having trouble understanding that n ^ logb (a) is polynomial less than or greater than f (n).

In my class slides about the master method, the first example uses the repetition T (n) = 4T (n / 2) + 1 and suggests the possibility that case 1 holds. n ^ logb (a) would be n ^ 2 and f (n) would be 1.

The foil indicates that f (n) is NOT polynomially smaller than n ^ 2. However, I do not understand this, because if you take an epsilon less than one and greater than zero, like 1/2, and you subtract that epsilon from n ^ 2, you would have n ^ 1.5 that would be even greater than f (n) which is one, for every n greater than one. So how is this not an example of being polynomially smaller?

## Why does the size of / etc / shadow never get larger or smaller when changing the password for a user on my system?

When I changed the password for a user in my Ubuntu system, I noticed that regardless of the length of the password I choose for the / etc / shadow file, it will remain the same size and never increase.

How is that possible?

## python – Tensorflow Advanced Indexing: Assign a smaller tensor to a position based on two index tensors

I want to create a zero tensor with the shape (3,4,2,2) and insert a (3,4) tensor at the position given by two (3,1) sensors.

Sample code: The corresponding numpy operation for arrays is as follows:

``````Output = np.zeros ((3,4,2,2))
bbox = np.arange (3 * 4) .reshape (3,4)
x = np.array ([0,0,1])
y = np.array ([1,1,1])

output[np.arange(3),:,x,y] = bbox
``````

How can I do something similar with Tensorflow?

NOTE: I actually want to work with a tensor of size (32,125,32,32). The above is a simple code for playback

## Disk Utility – Problems Cloning the OS X Drive to a Smaller Size

I am trying to move my OS X installation to a smaller hard drive because I intend to switch to a different operating system. However, this takes much longer than planned, and I hope someone can help me here.

The SSD, which now includes OS X, is divided into 4 partitions: EFI, Yosemite, Recovery HD (connected to Yosemite) and El Capitan. I've resized each partition (except EFI of course) and moved it to the left so that now only the first ~ 120 GB of hard disk is used, the rest is unassigned. Also note that this is a Hackintosh, so there are slight differences in the bootloader and content of EFI. This SSD works fine on all partitions, and Disk Utility detects no problems.

First of all, I tried to create partitions on the hard disk that start and end on the same sectors as the SSD (with gpt in the iirc terminal) (and then use Disk Utility (later tried with Gparted) to move the original partitions to the new ones copy and fix the hard disk to fix the partition table.This did not work – the hard disk was not bootable.

I've read on this and other websites that people use the Disk Utility to easily recover a larger hard drive with enough free space in a smaller one, and it just works. I tried the same thing, but I get a strange error (OSStatus error 6): `The volume is not of type Apple_HFS or Apple_UFS`, This is not the case with the exception of EFI. The target disk had an empty partition that was formatted in HFS +. However, the Disk Utility reported the error before the target could be verified. Note that I've tried this from El Capitan, Recovery HD and a separate USB stick from High Sierra Installer.

I tried to create an image of the entire disk. I formatted another 500 GB hard drive in GPT with an HFS + partition and used it as the target for the image file. However, the Disk Utility complained that it needed a disk space as large as the source disk, even if the image was to be compressed.

The use of CloneZilla did not get me much further. When trying to try disk-to-disk clones, there was an immediate error – even after I had chosen the option of not checking the size of the target disk based on the source (I will do this again tomorrow with a new SATA USB adapter try that I got today). Like many Linux tools, HFS + is poorly supported by CloneZilla. I also tried to create an image of the disk with Clonezilla. It seems to work fine and copying the data from each partition is complete, but just before the end it found an error and interrupted the operation, rendering the image useless (I did not record the actual error here, I can run it again and report.) if you think it may be relevant.). The image was transferred to the same 500 GB drive that was previously used with the Disk Utility, but only as exFAT.

Then I accepted commercial software. I tried Carbon Copy Cloner, which allows the user to clone only individual volumes at the same time. I tried to clone all the content, but after that the drive was no longer bootable. I later tried to remove the EFI partition from the SSD, but it made no difference. Note that the individual volumes on the newly cloned drive were properly booted when I started the bootloader (in my case, Clover) from another hard drive (the SSD or the installation USB). The same happened after trying a few other methods.

At this point, I have no ideas, and that gets a bit frustrating. What do I survey? How can I clone this plate and just use it as if it were the original? Thanks for your help.

## Redhat – Clonezilla error & # 39; partition size is smaller & # 39; during a V2V or P2V action

I am trying to use Clonezilla to migrate some computers (Red Hat Linux) to Virtual, and I have also tried to do the same migration by performing a simulation between some Hyper-V to VmWare (V2V) virtual machines.

I am using the latest version of Clonezilla and using the clonezilla option for network cloning.
The process starts properly, but after a while the error is aborted. The size of the target partition (xxxx MB) is smaller than the source (xxx MB).

I've used all sorts of options for partitions since auto-resizing also disabled checking, and so on, but it always fails.
I've also created a destination disk with more storage space

Any suggestions on how this problem could be solved?

Using the VMware converter is not an option for the computers that need to be migrated. We have other problems.

greetings

## Encoding Theory – Do you prove that the MinAveCodeLen of a product information source is smaller than the sum of the multiplicand and multiplier sources?

The product of 2 independent sources $$(S_A, P_A)$$ and $$(S_B, P_B)$$ is defined as

$$(S, P) text {s.t. } S = {s_As_B | s_A in S_A, s_B in B } text {and} P (s_As_B) = P_A (s_A) cdot P_B (s_B) , forall s_A in S_A, s_B in S_B$$

and MinAveCodeLen is the minimum average codeword length corresponding to the average codeword length of a Huffman coding.

The problem is to prove

$$mathrm {MinAveCodeLen} (P) leq mathrm {MinAveCodeLen} (P_A) + mathrm {MinAveCodeLen} (P_B)$$

The original problem is quite confusing. I am asked to prove $$H (P_A) + H (P_B) = H (P)$$ in the previous part I tried to connect the problem with it $$H$$ initially without progress.

## matlab – iteration through a matrix using a smaller matrix

I've been struggling with it for some time now. I have a little matrix `s` for example, and a larger matrix `B` As shown below.

``````B =
0 0 0 0 0 0 1 1
1 1 0 0 1 0 1 1
1 1 0 1 0 0 1 1
1 1 1 0 0 0 1 0
0 0 1 1 1 0 0 1
0 0 0 1 1 1 1 1
1 1 1 0 0 0 1 0
0 1 1 0 1 1 0 0

s =
1 1
1 1
``````

What I want to do is an iteration `B` With `s` and compare the values. If all values ​​in `s` equal to the values ​​in `B` (the small section of `B`), then the answer is 1, if not 0.

The `1er` and `0s` would also be placed in a matrix.

This is what I've done so far, but unfortunately it does not iterate step by step and does not create a matrix.

``````s = one (2,2)

B = Randi[0 1]8.8)

f = zeros (size (B))

[M,N]= Size (B); % the larger array
[m,n]= Size (s); % and the smaller ...

for i = 1: M / m- (m-1)
for j = 1: N / n- (n-1)
if all (s == B (i: i + m-1, j: j + n-1))
disp ("1")
otherwise
disp ("0")
The End
The End
The End
``````

Any help would be appreciated!

## dnd 5e – Is the summon of smaller demons stricter than the summoning of animals?

Summon small demons and summon animals that summon both creatures of equal value (but CA may summon a single CR 2 creature that does not allow SLD):

• Summon Beast Summon creatures that are friendly, where they summon
Little demon does not do it.
• Summon the incantation of the animals and obey your orders
Demons & # 39; charge will not.
• Summon Beasts can be improved by spending level 5, 7 magic slots
and 9, where the evocation of little demons is improved by spells
levels 6 and 8 and does not match the final CA Magic Slot
Update.

If someone had the opportunity to cast one of the two spells, why would someone summon lesser demons?