Can you use
irandom(-10,10)
to generate negative numbers? Or does this function provides only number >=0?
There is no information in documentation of GML.
A few examples:
a = -1 * irandom(10);
a = -irandom(10);
a = irandom(20) - 10;
a = irandom_range(-10, 10);
Related
in the DVBS2 Standard the SRRC filter is defined as
How can i find the filter's time domain coefficients for implementation? The Inverse Fourier transform of this is not clear to me.
For DVBS2 signal you can use RRC match filter before timing recovery. For match filter, you can use this expression:
For example for n_ISI = 32 and Roll of factor = 0.25 with any sample per symbol you can use this Matlab code:
SPS = 4; %for example
n_ISI=32;
rolloff = 0.25;
n = linspace(-n_ISI/2,n_ISI/2,n_ISI*SPS+1) ;
rrcFilt = zeros(size(n)) ;
for iter = 1:length(n)
if n(iter) == 0
rrcFilt(iter) = 1 - rolloff + 4*rolloff/pi ;
elseif abs(n(iter)) == 1/4/rolloff
rrcFilt(iter) = rolloff/sqrt(2)*((1+2/pi)*sin(pi/4/rolloff)+(1-2/pi)*cos(pi/4/rolloff)) ;
else
rrcFilt(iter) = (4*rolloff/pi)/(1-(4*rolloff*n(iter)).^2) * (cos((1+rolloff)*pi*n(iter)) + sin((1-rolloff)*pi*n(iter))/(4*rolloff*n(iter))) ;
end
end
But if you want to use SRRC, there are two ways: 1. You can use its frequency representation form if you use filtering in the frequency domain. And for implementation, you can use the expression that you've noted. 2. For time-domain filtering, you should define the FIR filter with its time representation sequence. The time representation of such SRRC pulses is shown to adopt the following form:
Say I have a function that generates random integers between say (1,10).
Then, I define a (for loop) which has 5 iterations.
This (for loop) calls the function defined above, and then it checks the value of the integer generated by the function. Depending on the value of the integer, the variable "cost" is decided.
function integer = UniformInt(a, b)
integer = min( floor( rand()*(b-a) ) + a , b);
endfunction
for i=1:5
x(i) = UniformInt(1,10);
if (x(i)<4) then
cost(i) = 15;
elseif (4<=x(i) && x(i)<=8) then
cost(i) = 27;
else
cost(i) = 35;
end
end
Now, when I run that and find x, say the values generated are:
5.
9.
5.
2.
2.
And so, the different cost values will be:
27.
35.
27.
15.
15.
This is all good so far. Now, what I want to do with these results is:
Check how many times each value of x appeared. I can do this via Scilab's tabul function:
9. 1.
5. 2.
2. 2.
Now, what I really want to code is:
x=9 only showed up once, so, the average of cost is 35/1 = 35.
x=5 showed up twice, so, the average of cost is (27+27)/2 = 27.
x=2 showed up twice, so, the average of cost is (15+15)/2 = 15.
How would I do that?
For posterity, a code in which the answer provided by user #Stéphane Mottelet would be useful (because my code above is trivial) is as follows:
function integer = UniformInt(a, b)
integer = min( floor( rand()*(b-a) ) + a , b);
endfunction
for i=1:5
x(i) = UniformInt(1,10);
if (x(i)<4) then
cost(i) = 15*rand();
elseif (4<=x(i) && x(i)<=8) then
cost(i) = 27*rand();
else
cost(i) = 35*rand();
end
end
Now the cost values are multiplied by a random number, and so,
if the value of say x=10 showed up 2 times, the average cost when x=10 will not simply be (35+35)/2.
I would do like this, but the answer is quite trivial since for now the value of cost is the same for a given x value (I suppose your real application draws random values of cost)
t = tabul(x);
for k = 1:size(t,1)
avg(k) = mean(cost(x == t(k)));
end
Given the following code which encodes a number - how can I calculate the maximum number if I want to limit the length of my generated keys. e.g. setting the max length of the result of encode(num) to some fixed value say 10
var alphabet = <SOME SET OF KEYS>,
base = alphabet.length;
this.encode = function(num) {
var str = '';
while (num > 0) {
str = _alphabet.charAt(num % base) + str;
num = Math.floor(num / base);
}
return str;
};
You are constructing num's representation in base base, with some arbitrary set of characters as numerals (alphabet).
For n characters we can represent numbers 0 through base^n - 1, so the answer to your question is base^10 - 1. For example, using the decimal system, with 5 digits we can represent numbers from 0 to 99999 (10^5 - 1).
It's worth noting that you will not ever use some sub-n length strings such as '001' or '0405' (using the decimal system numerals) - so any string starting with the equivalent of 0 except '0' itself.
I imagine that, for the purpose of a URL shortener that is allowed variable length, this might be considered a waste. By using all combinations you could represent numbers 0 through base^(n+1) - 2, but it wouldn't be as straightforward as your scheme.
How to get 6 decimal precision using vb.net as in this example (7090982.885183 (6 decimal places precision)) i.e i want to read the .885183 in my previous sample as 6 decimal only.
The javascript for the above looks like :
//declare variables and assign calculated values
var HashA = OrdNo * Amt;
var HashB = MerchID * Amt;
var HashC = MerchID * OrdNo;
var TotalHash = String((HashA + HashB + HashC) / (parseInt(MerchID) + parseInt(RCode)));
//assign only 6 decimal places value
if (TotalHash.indexOf(".") != -1)
TotalHash = TotalHash.substr(0,TotalHash.indexOf(".")+7);
else
TotalHash = TotalHash + ".000000";
document.form1.HashCount.value = TotalHash;
}
I need to read this no 7090982.8851830000011 as this format 7090982.885183
What about using % operater like
you have an variable a and variable decimalresult you should code it like this
decimalresult=a % 1000000
In this example it should be
decimalresult= 7090982.885183 % 1000000
decimalresult = 885183
If you have a Decimal and you want to get the value after the decimal dot, you can do
result = input - Math.Floor(input)
I need to define a set of parameters that have a natural recursive relation.
Here is a MWE where I try to define the factorial function over a set of (nine) parameters S:
$title TitleOfProblem
set S / s1*s9 /;
alias(S, S1, S2);
set delta1(S1,S2);
delta1(S1,S2) = yes$(ord(S1) + 1 = ord(S2));
parameter f(S);
f(S) = 1$(ord(S) = 1) + (ord(S) * sum(S1$(delta1(S1, S)), f(S1)))$(ord(S) > 1);
display f;
"delta1" is a relation containing pairs of elements in sorted order that differ by 1. Logically, the definition of f matches the definition of the factorial function (for inputs 1 to 9), but GAMS doesn't seem to like that f is defined recursively. The output of GAMS compilation looks something like this:
f(S) = 1$(ord(S) = 1) + (ord(S) * sum(S1$(delta1(S1, S)), f(S1)))$(ord(S) > 1);
$141
141 Symbol neither initialized nor assigned
A wild shot: You may have spurious commas in the explanatory
text of a declaration. Check symbol reference list.
Question:
Is it possible to recursively define a parameter in GAMS? If not, what is a work-around?
(P.S. Someone with enough rep should create a tag "GAMS" and add it to this question.)
Someone showed me a solution for my example using a while loop. However, this solution is specific to factorial and does not generalize to an arbitrary recursive function.
$title factorial
set S / s1*s9 /;
parameter f(S);
parameter temp;
Loop(S,
temp=ord(s);
f(S)=ord(s);
While(temp > 1,
f(S) = f(S) * (temp-1);
temp = temp - 1;
);
);
display f;