I want to perform an integer division in Octave (I'm using the latest version 5.1.0). I tired doing idivide(5, 2, "round") which should produce 3. The Documentation says for using idivide with round:
Calculate a ./ b with the fractional part rounded towards the nearest integer.
However, the result I get is 2.5000. What am I doing wrong?
Edit: sorry I used the wrong parameter when initially writing the question. Calling the function with fix works perfectly fine (e.g. idivide(5, 2, "fix") returns 2), I get the problem when using round.
Edit: The below is important for Matlab, in Octave the originally posed question (fix) gave the expected answer.
At least one of the input arguments must be an integer, hence this should work
idivide(5, int32(2), 'fix')
But be sure that this is what you want. idivide will return an integer class object which has various consequences if you aren't expecting it.
For example compare with an alternative solution which returns a double
idivide(5, int32(2), 'fix')*0.9
ans =
int32
2
fix(5/2)*0.9
ans =
1.8000
Related
I recently read this article.
The problem is about finding the smallest binary digit multiple of a given number x and the solution given there uses a binary tree starting from '1'. At each stage, it considers to topmost string and if it is not a multiple of x, it generates two more strings by concatenating a '0' and a '1' to the end of the string.
However, to optimize the solution the each possible solution s is checked for int(s) mod x.
If the remainder has occurred previously then that path is abandoned. I cannot figure out why this is happening.
I have been struggling with some questions from my study guide and really am stuck - I have asked the lecturer for help but his answer was literally "but it's been done for you" (referring to gauss_seidel code that was written) - to which I think he missed the point. I'm struggling to understand the actual question and how to approach it.
The first question reads as follows:
Define the 100x100 square matrix A and the column vector b by:
A(ij)=I(ij)+1/((i-j)2+1) b_(i)=1+2/i 1<=i j<=100
where I_(ij) is the 100x100 identity matrix (i.e 1 on the main diagonal and 0 everywhere else). Solve for x using both the Gauss-Seidel method and the A\b construct.
We have written the code for the gauss_seidel method, and i think i understand what it does mostly, however, i do not understand how the above question fits into the method. I was thinking that i'm supposed to do something like the following in the octave window then calling the gauss_seidel method:
>> A=eye(100,100);
>> b= (this is where i get slightly confused)... I've tried doing
>> for b=1:n;
>> b=1+(2/n);
That is question 1.
Question 2 I have given an answer and asked him about but he has not responded.
It reads: The Hilbert matrix is a square n x n matrix defined by:
H_(ij)n = 1/i+j+1
Define bn to be a column vector of dimension n, and with each element 1. Construct bn and then solve for x, Hn xn=bn in the cases n=4.
What i did here was simply:
>> b=ones (4,1);
>> x=hilb(4)\b;
and then it gave me the output of x values. Im not sure if what i did here was correct... since it doesnt mention using any method at all it just says solve for x.
Im not sure how to relate the lecturers reply to understanding the problem.
If you could help me by maybe letting me know what im missing or how i should be thinking about this, it would really help.
the gauss_seidel code looks like this:
function xnew=gauss_seidel(A,b,xold)
n=size(A)(1);
At=A;
xnew=xold;
for k=1:n
At(k,k)=0;
end
for k=1:n
xnew(k)=(b(k)-At(k,:)*xnew)/A(k,k);
end
endfunction
Ive been writing pseudo since last Monday and I am only a little bit clearer on what the code does.
A(ij)=I(ij)+1/((i-j)2+1), b(i)=1+2/i, 1<=i, j<=100
All this is really saying is that we have to create A and b in such a way that i>=1 and j<=100. After doing that, you simply solve using the Gauss Seidel method.
So we'd create b like this:
b=zeros(100,1);
for k=1:100
b(k) = 1+(2/k);
end
This will create a column vector with a size of 100x1 with all the values that satisfy b(i)=1+2/i where i (or in the code,'k') was greater or equal to 1.
Then to create A :
myMatrix=zeros(100,100);
for i=1:100
for j=1:100
myMatrix(i,j) = 1/(((i-j)^2) + 1);
end
end
A=eye(100) + myMatrix;
Now we have created A in such a way that it equals A(ij)=I(ij)+1/((i-j)2+1) where i was greater or equal to 1 & j was less than or equal to 100.
The rest of the question is basically asking to to solve for the values of x using the Gauss Seidel method.
So it be something like this :
y=iterative_linear_solve(A,b,x0,TOL,max_it,method);
Don't forget about creating x0 as the initial assumption, tolerance and max iterations etc.
In terms of question 2, you did exactly what I would have done. I think you're good with that.
I'm not too sure how to answer this :
If you could help me by maybe letting me know what im missing or how i
should be thinking about this, it would really help.
All I can really say is that you need to look at the problems in such a way that you see Ax=b. For example in the first question we started by making b, and then A. After that we simply applied the A\b construct or the Gauss Seidel method and got our answer.
And that's essentially what you did for the second question.
Lastly, are you a UNISA student by chance? I am, haha. I've been struggling with this on my own for a while. The study guides don't seem to give a lot of info.
In my report I'm trying to remove the decimals without rounding. I'll be using this to set the minimum value in the vertical axis of the area chart.
So I tried =Format(98.56, "N0"), but this returns 99, which is incorrect. It should return 98.
I've been searching specifically for SSRS, but most of the results are for tsql.
My question: How can I remov decimals in SSRS without rounding?
Thanks
Try using "Floor". It effective rounds down to the nearest integer. You'll find this under the Math functions.
=Floor(Fields!Number.Value)
Note, there's also a Floor function in Transact-SQL that works the same way in case you need to do some of the processing in your SQL script.
Update based on request in comments
If you wanted to achieve the same result after the decimal point, all you need is a little algebra.
=Floor((Fields!Number.Value*10))/10
That should turn 99.46 into 99.4. Given that it shaves off the remainder, you could then tack on any additional zeroes you wanted.
I ended up converting to Int. The following expression in SSRS returns 98:
=Int(98.56)
I know the question is quite old, but as I ended up here having the same question I would like to share my answer:
While FLOOR and CEILING are fine if you take extra measures to handle numbers <0 or know they are always >=0, the easiest way to simply strip off the decimals is to use
=Fix(Fields!Number.Value)
FIX only returns the integer part of a number, without any rounding or transformation. For negative numbers Int rounds up.
Source: Examples for Fix, Floor and Ceiling
Source: Difference between Int and Fix
I'm currently translating an application from actionscript-3 to Java code and got stuck with a variable assignment problem.
There is such block in as3 application:
var num:*=0;
...
num = 5.5;
As far as I understand AS3, variable is declared of an unknown type, which is resolved during the first assignment =0 meaning it will become int. Am I right?
So does that mean that by assigning 5.5 to it, the Number will be converted to int, and I will have num==5 in the result? Or will it become Number after assigning Number to it?
Thanks in advance.
Added:
Sorry, but I don't have any Flash environment to test it myself. I'm converting one of the utility methods from actionscript to Java and got stuck with this problem.
Added 2:
The question is, if num will contain 5 or 5.5 at the end of this block?
The standard datatypes for both integer and floating point data is Number. If you have 0 at the beginning, then it is a Number. Neither an int nor a double.
So, yes, the variable will contain 5.5 in the end.
Try tracing the number after second assignment, but I would guess that it will become Number.
in xxxx.mxml (from flex) i have called the remote remote method (of java) the method return type is float
in the xxxx.mxml's remote objects result handler i need get the float values as Numeric.....or String..i tried with string...i did Alert.show to see the value some times i get exact value for eg, 0.5 is the value returning from java methid but here it will show 0.50000454...so on..how get the exact value?
It is because of the way floating point numbers are stored; basically they can't be stored precisely. A quick search in SO would reveal a lot of threads about this. Also read "What Every Computer Scientist Should Know About Floating-Point Arithmetic"
Thus the problem of getting the exact value boils down to what you define exact to be. Try rounding it to a given number of floating points at java end, convert the rounded number to a string (I'm not sure if this conversion would preserve the precision) and send that string.