Assume, I have 4 boxes. I would like to write down a propetry (e.x. P) of 4 boxes from time t=0 till t=5s next to each other in Fortran, like the one in the figure I have attached. How can I do it in Fortran?! NOTE, I do not know the the valueof P for next time step when i write it down.
enter image description here
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I was faced with creating a program that can tell a user how much interest will be added to a product after any arbitrary number of years. I had to use a loop to estimate the new price, among other things.
The problem I ran into was in the creation of the loop. I didn't know how to make it stop at any specific year that a user chose. What I did is made a for loop that outputted the loop for the next 99 years. This was my loop:
for (time>0; time<=99; time++) where time was the number of years from today.
This is obviously not ideal. I wrote this in frustration from not knowing how to create a loop that can end wherever the user wants. How can I create a loop that terminates at any desired year?
for (time>0; time<=99; time++)
This will stop at a predefined number, i.e. 99. To make it stop at a number given by user you need to:
Get the number from the user and save it in a variable
Replace 99 with the variable in your loop
Okay, so this is going to be very complicated to explain through text but I will do my best to try.
I am making a universal calculator where one of the function of the calculator is to process a formula when given an unknown number of variables. I have seen some ways to do this but for how i'm trying to use this calculator, it wont work.
Example for sum of function:
while (cin >> input)
count++;
Normally this would work but the problem is that I can't have the user input the values over and over again for one formula like for this formula: Formula Example
(Sorry its easier for me to explain through a picture) In it there are multiple times where I have to use the same numbers over and over again. Here is the entire process if you need it to understand what I'm saying:
Entire problem
The problem is that normally I would add another float for every point graph but I don't know ahead of time number of floats the user is going to enter in. The ideal way to do this is for the program to ask the user for all the points on the table and for the user to input those points in a format like: "(1,2) (2,4) (3,6)..."
Thinking ahead, would I make a function where the program creates an integer and assigns the integer to a value on the fly? But then how would the actual math formula interact with the new integers if they haven't been created yet?
Talking about this makes my head hurt....
I actually want to say more:
One idea that I tried to make in my head was something like
string VariableName = A [or something]
Then you would reassign VariableName = "A" to VariableName = "B" by something like VariableName = "A"+ 1 (which would equal B).
Then you would repeat that step until the user inputs a invalid input. But obviously you can't do math with letters so I wouldn't know how to do it.
I think that you are overthinking this. It's pretty simple and it doesn't need to store the input values.
The main thing to note is that you need to compute (step 2) the sum of the values of X and Y, the sum of their product and the sum of X squared. To compute the sum of a lot of values you don't need all the values together, but just one at the time. Exactly as when a user provides them. So declare four variables: sx, sy, sxy, sxx. Initialize them to 0. At every couple of X and Y you get, add it to sx and sy, add their product to sxy and the product of X with itself to sxx.
Now you've got all you need to compute the final result for a and b.
Anyway a good C++ book would be useful.
This problem is a precursor as well as the design problem of a program I'm working upon.
We have 3 types of cards - Red (R), Green (G) and Blue (B). And they have to be placed on trays where there are multiple slots where each slot can hold exactly one card (i.e, number of cards in a filled tray at any given time = number of slots in the tray). The player/user is given a choice of choosing from the following options:
3-slot tray, where any card type (R/G/B) can occupy any slot. for example, RRG, RGB, BRR etc.
4-slot tray, where the first slot can be occupied by only one of the card types G or B and the remaining 3 can be occupied by any of the the card types. for example, BRRG, GRGB, BBRR etc.
5-slot tray, where the first slot can be occupied by only one of the card types G or B and the remaining 4 can be occupied by any of the the card types. for example, GRRBG, GRRGB, GBRRG etc.
Now, with the program, I would like to:
validate the condition(s) for 4-slot tray and 5-slot tray
generate an array (a list in python) to store the permutation entered by the player/user. In all, the 3-slot tray has 27 (3*3*3), the 4-slot tray has 54 (2*3*3*3) and the 5-slot tray has 162 (2*3*3*3*3) possible permutations and combinations.
map each of these unique permutation to another array of numbers (let us call it the number list). For example, I want to map the permutation BGRG to [1,1,2,3] (which is based on the logic i[n]=1 for n=0,1 and i[n]=n for n>1); RGG to [1,1,2] and so on.
The requirement, put concisely, is:
accept the user input
validate the input according to the conditions
generate the array number list
I can always create a hard-coded multi-dimensional array/list, but I want to write a function which is flexible to any change in the logic (as mentioned in the last point above) and generate the lis. Is there an optimized, pythonic (I'm aware that python is smart with data structures and strings and can do things neatly with fewer lines of code) way to do this? Isn't a 3D list the best way to achieve this?
Ok, I just added a new feature to my student manager program (a console program written in c++) , it is a console application and my program print dates on which particular student is absent in a list format
by saying list format i mean 1 date on 1 line
this is how output looks like for student who is absent 5 times
1. 04/05/2016,Monday
2. 05/05/2016/Tuesday
3. 06/05/2016/Wednesday
(Assume dates are correct)
now since these are only 3 records that are printed on the screen, a user would not require scrolling down,
but in a case of 300 dates , it prints all dates but when i scroll up I'm not able to reach back to 1st date, for example, I'm only able to see last 147 Records only
and I'm not able to scroll my console window to 1st record.
I know many other ways to solve this problem (like displaying 10 records or 100 records at a time) but I want to know how can i solve this particular problem
please give answer considering me as a beginner. :)
Thank You.
(as far as code is concerned, i can assure you its nothing special, just a while loop that keeps on printing dates until certain terminating condition is met )
I’m not specialist in signal processing. I’m doing simple processing on 1D signal using c++. I want really to know how I can determine the part that have the highest zero cross rate (highest frequency!). Is there a simple way or method to tell the beginning and the end of this part.
This image illustrate the form of my signal, and this image is what I need to do (two indexes of beginning and end)
Edited:
Actually I have no prior idea about the width of the beginning and the end, it's so variable.
I could calculate the number of zero crossing, but I have no idea how to define it's range
double calculateZC(vector<double> signals){
int ZC_counter=0;
int size=signals.size();
for (int i=0; i<size-1; i++){
if((signals[i]>=0 && signals[i+1]<0) || (signals[i]<0 && signals[i+1]>=0)){
ZC_counter++;
}
}
return ZC_counter;
}
Here is a fairly simple strategy which might give you some point to start. The outline of the algorithm is as follows
Input: Vector of your data points {y0,y1,...}
Parameters:
Window size sigma.
A threshold 0<p<1 defining when to start looking for a region.
Output: The start- and endpoint {t0,t1} of the region with the most zero-crossings
I won't give any C++ code, but the method should be easy to implement. As example let us use the following function
What we desire is the region between about 480 and 600 where the zero density higher than in the front. First step in the algorithm is to calculate the positions of zeros. You can do this by what you already have but instead of counting, you store the values for i where you met a zero.
This will give you a list of zero positions
From this list (you can do this directly in the above for-loop!) you create a list having the same size as your input data which looks like {0,0,0,...,1,0,..,1,0,..}. Every zero-crossing position in your input data is marked with a 1.
The next step is to smooth this list with a smoothing filter of size sigma. Here, you can use what you like; in the simplest case a moving average or a Gaussian filter. The higher you choose sigma the bigger becomes your look around window which measures how many zero-crossings are around a certain point. Let me give the output of this filter together with the original zero positions. Note that I used a Gaussian filter of size 10 here
In a next step, you go through the filtered data find the maximum value. In this case it is about 0.15. Now you choose your second parameter which is some percentage of this maximum. Lets say p=0.6.
The final step is to go through the filtered data and when the value is greater than p you start to remember a new region. As soon as the value drops below p, you end this region and remember start and endpoint. Once you are finished walking through the data, you are left with a list of regions, each defined by a start and an endpoint. Now you choose the region with the biggest extend and you are done.
(Optionally, you could add the filter size to each end of the final region)
For the above example, I get 11 regions as follows
{{164,173},{196,205},{220,230},{241,252},{259,271},{278,290},
{297,309},{318,327},{341,350},{458,468},{476,590}}
where the one with the biggest extend is the last one {476,590}. The final result looks (with 1/2 filter region padding)
Conclusion
Please don't be discouraged by the length of my answer. I tried to explain everything in detail. The implementation is really just some loops:
one loop to create the zero-crossings list {0,0,..,1,0,...}
one nested loop for the moving average filter (or you use some library Gaussian filter). Here you can at the same time extract the maximum value
one loop to extract all regions
one loop to extract the largest region if you haven't already extracted it in the above step