I've been looking around on the web for this but cannot find anything.
Is there a way to use the CGAL::mod() function with 2 doubles? I can do
CGAL::mod(2,3) but not CGAL::mod(2.0,3.5) for example.
I get errors like this on compiling:
error: no match for call to ‘(CGAL::Algebraic_structure_traits_base<double, CGAL::Null_tag>::Mod {aka CGAL::Null_functor}) (const int&, const double&)’
Am I doing something wrong? From the documentation of the mod() function I understand that both arguments are of any tipe and that it can calculate it whilst compatible? I really don't understand that part, it's really technical but I hope you can help me.
Related
I am facing this problem as when I am trying to build the code using ANSI C, as I was practicing writing in it and dealing with its rules, it tells me invalid type conversion and I don't know what to do.
this is the code line that makes the error, it is a pointer to function:
((CanIf_FuncTypeCanSpecial)(entry->CanIfUserRxIndication))(
entry->CanIfCanRxPduHrhRef->CanIfCanControllerHrhIdRef,
entry->CanIfCanRxPduId,
CanSduPtr,
CanDlc,
CanId);
and this is howentry->CanIfUserRxIndication is declared, as void *CanIfUserRxIndication;
and this is how CanIf_FuncTypeCanSpecial is declared, as
typedef void (*CanIf_FuncTypeCanSpecial)
(uint8 channel, PduIdType pduId, const uint8 *sduPtr, uint8 dlc, Can_IdType canId);
every parameter in the conversion type is the same type as the input parameters except the first one entry->CanIfCanRxPduHrhRef->CanIfCanControllerHrhIdRef it is from type enum not uint8.
You can find the code on GitHub.
and also the MISRA Rule is telling me this:
#1398-D (MISRA-C:2004 11.1/R) Conversions shall not be performed between a pointer to a function and any type other than an integral type
I tried to convert from enum to uint8 to make all of the parameters as what the type conversion CanIf_FuncTypeCanSpecial takes, but nothing happened.
If I understand correctly, you are trying to cast an existing function to match a function pointer declaration that has a differing argument type. You can cast the parameters and call such a function, but because function pointers themselves may be used anywhere in the program, at the places where they would be used the code would not know what to cast (which may result in a size difference) this is illegal.
Usually string_view is used for function parameters like this:
void fval(std::string_view sv);
void fcref(std::string_view const &sv);
Which is better?
const reference is 8 bytes and string_view is usually twice that, e.g. 16 bytes.
However, if not inlined or optimized away, const reference might have two indirections - one for the ref, second for the pointer inside.
How STL doing it?
We usually pass string_views by value.
Examples from the C++20 draft:
Formatting
Time Zone Lookup
I'm trying to make some print statements in ROOT using Info, as in
Info("execute()","the pt of the jet = %.2f Gev", (*jets_itr)->pt());
and I am trying to find some documentation that will tell me what symbols to use to use for ints, doubles, etc (I think know from another source that .2f is a float, but otherwise I'm just guessing).
Thanks
you can find the full list here:
http://www.cplusplus.com/reference/cstdio/printf/
I am trying to follow another SO post and implement sqrt14 within my iOS app:
double inline __declspec (naked) __fastcall sqrt14(double n)
{
_asm fld qword ptr [esp+4]
_asm fsqrt
_asm ret 8
}
I have modified this to the following in my code:
double inline __declspec (naked) sqrt14(double n)
{
__asm__("fld qword ptr [esp+4]");
__asm__("fsqrt");
__asm__("ret 8");
}
Above, I have removed the "__fastcall" keyword from the method definition since my understanding is that it is for x86 only. The above gives the following errors for each assembly line respectively:
Unexpected token in argument list
Invalid instruction
Invalid instruction
I have attempted to read through a few inline ASM guides and other posts on how to do this, but I am generally just unfamiliar with the language. I know MIPS quite well, but these commands/registers seem to be very different. For example, I don't understand why the original author never uses the passed in "n" value anywhere in the assembly code.
Any help getting this to work would be greatly appreciated! I am trying to do this because I am building an app where I need to calculate sqrt (ok, yes, I could do a lookup table, but for right now I care a lot about precision) on every pixel of a live-video feed. I am currently using the standard sqrt, and in addition to the rest of the computation, I'm running at around 8fps. Hoping to bump that up a frame or two with this change.
If it matters: I'm building the app to ideally be compatibly with any current iOS device that can run iOS 7.1 Again, many thanks for any help.
The compiler is perfectly capable of generating fsqrt instruction, you don't need inline asm for that. You might get some extra speed if you use -ffast-math.
For completeness' sake, here is the inline asm version:
__asm__ __volatile__ ("fsqrt" : "=t" (n) : "0" (n));
The fsqrt instruction has no explicit operands, it uses the top of the stack implicitly. The =t constraint tells the compiler to expect the output on the top of the fpu stack and the 0 constraint instructs the compiler to place the input in the same place as output #0 (ie. the top of the fpu stack again).
Note that fsqrt is of course x86-only, meaning it wont work for example on ARM cpus.
my question now is :
I have the variavle M which contains : 37.5 (as you see is integer)
I want to convert M in order to be string "37.5"
so 37.5 should became "37.5"
I try with function :
M2=integer_to_list(M)
but when I execute this function it displays this error :
** exception error: bad argument
in function integer_to_list/1
called as integer_to_list(37.5)
integer_to_list wont work in that situation because 37.5 is a float and not an integer. Erlang does have float_to_list, but the output is usually pretty unusable.
Instead, I would recommend looking into mochiweb project for pretty conversion of floats to lists. In particular, the mochinum module:
> M = 37.5,
> mochinum:digits(M).
"37.5"
#chops has a great answer, IMO (using mochinum:digits/1), but you might also get something out of looking at the io_lib module. For example:
8> io_lib:format("~.2f",[37.5]).
["37.50"]
9> io_lib:format("~.1f",[37.5]).
["37.5"]
I realize this might not be exactly what you are looking for, and in this case I think looking at/using the mochinum module is an efficient way to go, but io_lib is often overlooked and provides a really useful set of functions for formatting lists / strings