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I am using c++ on my project. However, when I try to make a simple division, it gives me a weird number.
for:
1.0 / 2.0 = -107374176.
1.0 / 3.0 = -107374176.
1 / 3 = -107374176.
any idea why this is happening?
0xCCCCCCCC, a typical value used for uninitialized memory, interpreted as a 32-bit float, equals -107374176. You're printing an uninitialized float value.
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Given N amd M how to check whether floor value of N!/M will be even value or odd value where N can go upto 10^5 and M can go upto 10^18.
Please help to check this condition in efficient way.
EDIT
My attempt : I first think of breaking N!=(2^a)(some odd value) and similarly for M but as the odd value of N! can be very large so i was thinking of some better solution.
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I have an array of type double. How do I get the 10 lowest values?
double values[1000];
This is what I've come up before:
double similar[num_img];
copy(begin(values), end(values), begin(similar)); //copy values to another variable
int elements = sizeof(similar) / sizeof(similar[0]);
sort(similar, similar + elements);
So that I could get the 10 values. But what I'm actually after is the indices.. So sorting it would not help, I guess.
Sort the array and grab the first 10 elements (values[0] through values[9]).
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this is maybe newbei question , but i dont know how to fast acces to real part of fftw_complex with FFFTW, i cant use .real() method,
I need convert this to double array, dynamic array in c++;
From the docs, 2 second Google search:
4.1.1 Complex numbers
The default FFTW interface uses double precision for all floating-point numbers, and defines a fftw_complex type to hold complex numbers as:
typedef double fftw_complex[2];
Here, the [0] element holds the real part and the 1 element holds the imaginary part.
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I need to write a program that will perform operations on float numbers higher than 10^100.
I can't use any arbitrary precision mathematics libraries that are not included in GCC package by default.
I have NO idea how how to go about it.
Can you point me in the right direction?
You can create a class that can store larger numbers. 12345678 equals to 1234 * 10e4 + 5678.
For large numbers I use string buffers and do manual computation on it. It is much overhead and slow but you get infinite precision.
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I am using openCV C++ libraries and calculated a double. It does the arithmetic but when I read out the number, prints out -1.#QNAN on the command prompt. What does that mean?
I am using a 64-bit i3 processor.
It means you got a quiet NAN, probably by dividing -Inf / Inf or multiplying something with -Inf, or perhaps casing a non-double into a double. It's not so much a precision error as much as it's an arithmetic exception.
EDIT: or adding/substracting Inf ... read more on NaNs here
That's not an error, read more about floating point here