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QUESTION
Using this link as a guide, https://www.geeksforgeeks.org/difference-float-double-c-cpp/#:~:text=double%20is%20a%2064%20bit,15%20decimal%20digits%20of%20precision. double is a 64 bit IEEE 754 double precision Floating Point Number (1 bit for the sign, 11 bits for the exponent, and 52 bits for the value), i.e. double has 15 decimal digits of precision , the below code does not maintain 15 decimal digits of precision. Rather, 14.
It is for simple projectile motion calculator, where, the range of a projectile launched at 30 degrees should match that of the same projectile launched at 60 degrees.
...ANSWER
Answered 2021-May-16 at 10:55double overloaded sin() and cos() do not maintain 15-digit decimal precision
It is not possible for any fixed-size numerical format to “maintain” a specific precision, regardless of whether it is floating-point, integer, fixed-point, or something else.
Whenever the result of an operation performed with real-number mathematics is not representable in the numerical format, only an approximation of the real-number result can be returned. The real-number result must be rounded to some representable value. This introduces a rounding error.
When there are multiple operations, the rounding errors may accumulate and compound in various ways. The interactions and consequences may be very complicated, and there is an entire field of study, numerical analysis, for it.
As a simple example, consider integer arithmetic, in which the resolution is 1. Yet, if we compute 17/3•5 with 17/3*5
, we get 25, where the real-number result would be 28⅓, and the integer result nearest the ideal result would be 28. So the computed result is off by three units from the best representable result (and 3⅓ from the real-number result) even though we only did two operations. Integer arithmetic cannot “maintain” 1 unit of precision.
In your sample, rounding errors occur in these operations:
- 9.80665 is converted to the
double
format. - The numeral for π is converted to the
double
format. a1
anda2
are each multiplied bypi
.- Those products are divided by 180.
- The sines and cosines of those quotients are taken.
2 * vy1
and2 * vy2
are divided byg
. (The multiplication by 2 does not introduce any rounding error as its result is exactly representable in binary-based floating-point.)- Those quotients are multiplied by
vx1
andvx2
. - Those products are converted to decimal for display.
Additionally, sin
and cos
are difficult to implement, and common implementations prefer speed and provide it at the cost of allowing a little additional error. Their results could be off by a few ULP (units of least precision), possibly more in bad implementations.
QUESTION
I'm trying to post json data in C++ with the restc-cpp library and I have this error:
...ANSWER
Answered 2021-May-05 at 09:53I have found the error. I have read the documentation about enable_if in type_traits standard library. It appears it is a check for integral_type, floating_point, ... in
QUESTION
I have different vim-scripts for different filetypes
...ANSWER
Answered 2021-Apr-23 at 15:09Vim already has a built-in mechanism for sourcing filetype-specific configuration files so reimplementing it, and in a non-portable way to boot, is totally pointless.
Here is how your directory structure should look like:
QUESTION
So I try to get started with cmake for some time now. I want to use rpclib from here. So I started a new project with main.cpp
and CMakeLists.txt
and copied the rpclib
as a subdirectory into my project:
My code is exactly the example from rpclib and looks like this:
...ANSWER
Answered 2021-Mar-05 at 12:37You're missing a target_link_libraries(RPC_Test PRIVATE rpc)
after the definition of the RPC_Test
target . rpc
here is the name of the library target defined in rpclib
's CMakeLists.txt
, not just the base name of the resulting binary artifact.
When using a target name with target_link_libraries
like that CMake will not only add -lrpc
to the linker invocation, but also automatically add the include directories necessary to use the library and ensure that the rpc
library is built before RPC_Test
. In particular, this means you can also remove the include_directories
call when you use target_link_libraries(RPC_Test PRIVATE rpc)
.
QUESTION
I am running VSCode from Windows over an SSH connection to a Centos 7 development machine and I get the error "Skipping CppCheck linter because lintOn 1 is not in 2." This was working perfectly and I have no idea what might have changed to provoke the error. I do not get any squiggles denoting issues in the code editor. I have been unable to find any help online.
My settings.json in the project .vscode directory reads:
...ANSWER
Answered 2021-Feb-09 at 08:05This would seem to be a bug in the extension and has been reported to the maintainer
QUESTION
Is there a way I can force VSCode to preview *.mdx
files as markdown just like it does for *.md
files? For reference see how Github shows preview of this mdx file
I know there's an extension MDX Preview but that's not working for next.js
project. see open issue.
I tried this vscode setting but doesn't work:
...ANSWER
Answered 2020-Dec-13 at 15:34In files.associations
you mention the languageId to use for a particular file extension
QUESTION
I'm using an Arduino Mega to control a CS1237 ADC. I'm sending a signal to the clock pin and after each clock pulse, waiting 1ms and then reading the response, according to the datasheet I found (via https://github.com/SiBangkotan/CS1237-ADC-cpp-library). This seems to be working in some capacity, because when I do Serial.println()
for each bit received, and for the resulting dataword, I get a 24 bit dataword that matches the 24 separate bits I got. However, when I take out the extra debugging uses of Serial.println()
that print each bit as they are received, I get a different dataword as well. It's 20 bits of all 1's every single time, instead of 24 bits of various 1's and 0s. I cant figure out why this extra debugging output in the serial communication channel should change the dataword that comes into the serial monitor?
Here's my setup and pre-setup code:
...ANSWER
Answered 2020-Nov-13 at 12:33From looking at the datasheet...
First when the chip boots... Al pins are input by default. You do not set your clock pin mode, so you have no clock. Also, the ADC could take up to 300 milliseconds to wake up. That is part of your boot sequence, the chip should be ready when you exit setup(). You may also include setting of any ADC registers in setup() as well. See datasheet startup sequence @ figures 5 and 6.
Also, if you want to try lower clock speeds, do not leave clck
high longer than 100us
From datasheet, 2.5: "When SCLK goes from low to high and stays high for more than 100μs, the CS1237 entersPowerDown mode, which consumes less than 0.1μA. When SCLK goes back low, the chip will resume normal operation."
QUESTION
I am using non-blocking IO where I simply try to write and read to a serial port. Reading of the serial port works as expected whereas writing doesn't.
This is how I've set up the serial line. As you can see, it is setup to non-blocking and canonical. Maybe some of the flags are redundant, but they are mostly taken from an example here: Serial setup example
...ANSWER
Answered 2020-Nov-13 at 00:53I am using
select
to wait for the IO resource to become available ... But even waiting 20 seconds, the device is still unavailable.
Your program is not behaving as you expect because you have not properly programmed the select() call:
QUESTION
~(background) I mostly code C on Linux but i want to have the ability to code C on Windows 10 every now and then, so i searched and found out VSCode will do the work (for the time being). Did some research, figured out some stuff i needed, but i have a problem with makefile.I have been using makefile in a basic level but it worked no problem on Linux, VSCode not at all.
~(problem) So am having the error in the picture and no matter what extension (for VSC) i tried i couldn't figure out how to run makefile and compile my code.
~(conclusion) From what i see, VSC can't find anything associated with the word 'make' wihich means i am missing some files, extensions or something else. I don't think i do something wrong with extensions, they are pretty straight forward on how they work. (i have listed what i tried at the end of the post)
[What extensions i tried]
Make: https://marketplace.visualstudio.com/items?itemName=technosophos.vscode-make
makefree: https://marketplace.visualstudio.com/items?itemName=pidesh.makefree
C/C++ Makefile Project: https://marketplace.visualstudio.com/items?itemName=adriano-markovic.c-cpp-makefile-project
Makefile Command Runner: https://marketplace.visualstudio.com/items?itemName=madmous.makefile-command-runner
...ANSWER
Answered 2020-Sep-28 at 14:35Firstly, I would ensure that make is installed on your system.
Secondly, if make is installed, make sure you are operating from the correct directory. If you open a terminal using Terminal > New Terminal and type in make, does it work. If so then you may just need to create a simple task that runs on an F5 press or whatever OR just type make in to build every time.
If make doesn't work, make sure you are using the directory containing the makefile as your WD or otherwise cd or set your settings in those extensions to use a subdir as the root.
QUESTION
I'm using the following Dockerfile to install grpc on a build image, build a cpp microservice and put that into a runtime container.
https://github.com/npclaudiu/grpc-cpp-docker/blob/master/Dockerfile
But the part that builds grpc/protobuf takes 2hours+ and that is for one service.
...ANSWER
Answered 2020-Sep-11 at 14:47You can create an intermediate image. Split your Dockefile into 2 parts after these lines:
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