I am creating a program in GP/Pari
foo()=
{
coefficient = vector(2);
coefficient[1] = 1;
coefficient[2] = 2;
UserNum = Vector(2);
UserNum[1] = 1;
UserNum[2] = 2;
n=2;
for( r=1,n,
sum = coefficient[r]* UserNum[r]^r );
}
Why do i get a compilation error :
variable name not expected
It appears the error lies in the FOR LOOP but I cant tell whats wrong with my FOR LOOP , can someone help me thanks !!!
The name sum is reserved for PARI/GP's built-in function. Just use another name. Your code can be improved as follows.
foo() = {
coefficient = [1, 2];
UserNum = [1, 2];
for(r = 1, 2, var = coefficient[r] * UserNum[r]^r);
}
Related
First of all, please understand that I'm not good at English.
I am studying react-hook.
I am looking at an example code, and the factors(?) is declared in the function component as follows.
const lottoNumbers = useMemo(() => getWinNumbers(), []);
const [winNumbers, setWinNumbers] = useState(lottoNumbers);
const [winBalls, setWinBalls] = useState([]);
and setWinballs were used as follows.
for (let i = 0; i < winNumbers.length - 1; i++) {
timeouts.current[i] = setTimeout(() => {
setWinBalls((prevBalls) => [...prevBalls, winNumbers[i]]); <--------
}, (i + 1) * 1000);
What does 'setWinBalls((prevBalls) => [...prevBalls, winNumbers[i]])' mean here?
I didn't know that the 'set' function could have a function parameter.
The function setWinBalls() is using an arrow function which returns an object. Spread syntax has been used inside the arrow function which simply adds the current winNumber which is winNumbers[i] to the array and stores the updated array into another variable.
//example to understand what spread syntax does
var exampleArray = [1, 2, 3];
exampleArray = [...exampleArray, 4];
//exampleArray will be [1, 2, 3, 4]
Now let us try and understand what this arrow function is doing. The for loop can be written this way:
for (let i = 0; i < winNumbers.length - 1; i++) {
timeouts.current[i] = setTimeout(() => {
var updatedBalls = (prevBalls) => [...prevBalls, winNumbers[i]];
//winNumbers[i] will be added to the end to prevBalls array and updated array will be stored in updatedBalls
setWinBalls(updatedBalls);
}, (i + 1) * 1000);
Hope the code is clear to you now.
We have a HashMap Integer/String and in Java we would iterate over the HashMap and display 3 key value pairs at a time with the click of a button. Java Code Below
hm.put(1, "1");
hm.put(2, "Dwight");
hm.put(3, "Lakeside");
hm.put(4, "2");
hm.put(5, "Billy");
hm.put(6, "Georgia");
hm.put(7, "3");
hm.put(8, "Sam");
hm.put(9, "Canton");
hm.put(10, "4");
hm.put(11, "Linda");
hm.put(12, "North Canton");
hm.put(13, "5");
hm.put(14, "Lisa");
hm.put(15, "Phoenix");
onNEXT(null);
public void onNEXT(View view){
etCity.setText("");
etName.setText("");
etID.setText("");
X = X + 3;
for(int L = 1; L <= X; L++ ){
String id = hm.get(L);
String name = hm.get(L = L + 1);
String city = hm.get(L = L + 1);
etID.setText(id);
etName.setText(name);
etCity.setText(city);
}
if(X == hm.size()){
X = 0;
}
}
We decoded to let Android Studio convert the above Java Code to Kotlin
The converter decide to change the for(int L = 1; L <= X; L++) loop to a while loop which seemed OK at first then we realized the while loop was running for 3 loops with each button click. Also Kotlin complained a lot about these line of code String name = hm.get(L = L + 1); String city = hm.get(L = L + 1);
We will post the Kotlin Code below and ask the question
fun onNEXT(view: View?) {
etCity.setText("")
etName.setText("")
etID.setText("")
X = X + 3
var L = 0
while (L <= X) {
val id = hm[L - 2]
val name = hm.get(L - 1)
val city = hm.get(L)
etID.setText(id)
etName.setText(name)
etCity.setText(city)
L++
}
if (X == hm.size) {
X = 0
}
}
We tried to write a For Next Loop like this for (L in 15 downTo 0 step 1)
it seems you can not count upTo so we thought we would use the hm:size for the value 15 and just use downTo
So the questions are
How do we use the Kotlin For Next Loop syntax and include the hm:size in the construct?
We have L declared as a integer but Kotlin will not let us use
L = L + 1 in the While loop nor the For Next Loop WHY ?
HERE is the strange part notice we can increment X by using X = X + 3
YES X was declared above as internal var X = 0 as was L the same way
Okay, I'll bite.
The following code will print your triples:
val hm = HashMap<Int, String>()
hm[1] = "1"
hm[2] = "Dwight"
hm[3] = "Lakeside"
hm[4] = "2"
hm[5] = "Billy"
hm[6] = "Georgia"
hm[7] = "3"
hm[8] = "Sam"
hm[9] = "Canton"
hm[10] = "4"
hm[11] = "Linda"
hm[12] = "North Canton"
hm[13] = "5"
hm[14] = "Lisa"
hm[15] = "Phoenix"
for (i in 1..hm.size step 3) {
println(Triple(hm[i], hm[i + 1], hm[i + 2]))
}
Now let's convert the same idea into a function:
var count = 0
fun nextTriplet(hm: HashMap<Int, String>): Triple<String?, String?, String?> {
val result = mutableListOf<String?>()
for (i in 1..3) {
result += hm[(count++ % hm.size) + 1]
}
return Triple(result[0], result[1], result[2])
}
We used a far from elegant set of code to accomplish an answer to the question.
We used a CharArray since Grendel seemed OK with that concept of and Array
internal var YY = 0
val CharArray = arrayOf(1, "Dwight", "Lakeside",2,"Billy","Georgia",3,"Sam","Canton")
In the onCreate method we loaded the first set of data with a call to onCO(null)
Here is the working code to iterate over the CharArray that was used
fun onCO(view: View?){
etCity.setText("")
etName.setText("")
etID.setText("")
if(CharArray.size > YY){
val id = CharArray[YY]
val name = CharArray[YY + 1]
val city = CharArray[YY + 2]
etID.setText(id.toString())
etName.setText(name.toString())
etCity.setText(city.toString())
YY = YY + 3
}else{
YY = 0
val id = CharArray[YY]
val name = CharArray[YY + 1]
val city = CharArray[YY + 2]
etID.setText(id.toString())
etName.setText(name.toString())
etCity.setText(city.toString())
YY = YY + 3
}
Simple but not elegant. Seems the code is a better example of a counter than iteration.
Controlling the For Next Look may involve less lines of code. Control of the look seemed like the wrong direction. We might try to use the KEY WORD "when" to apply logic to this question busy at the moment
After some further research here is a partial answer to our question
This code only show how to traverse a hash map indexing this traverse every 3 records needs to be added to make the code complete. This answer is for anyone who stumbles upon the question. The code and a link to the resource is provide below
fun main(args: Array<String>) {
val map = hashMapOf<String, Int>()
map.put("one", 1)
map.put("two", 2)
for ((key, value) in map) {
println("key = $key, value = $value")
}
}
The link will let you try Kotlin code examples in your browser
LINK
We only did moderate research before asking this question. Our Appoligies. If anyone is starting anew with Kotlin this second link may be of greater value. We seldom find understandable answers in the Android Developers pages. The Kotlin and Android pages are beginner friendlier and not as technical in scope. Enjoy the link
Kotlin and Android
To calculate an enhancement function for an input image I have written the following piece of code:
Ig = rgb2gray(imread('test.png'));
N = numel(Ig);
meanTotal = mean2(Ig);
[row,cal] = size(Ig);
IgTransformed = Ig;
n = 3;
a = 1;
b = 1;
c = 1;
k = 1;
for ii=2:row-1
for jj=2:cal-1
window = Ig(ii-1:ii+1,jj-1:jj+1);
IgTransformed(ii,jj) = ((k*meanTotal)/(std2(window) + b))*abs(Ig(ii,jj)-c*mean2(window)) + mean2(window).^a;
end
end
How can I reduce the calculation time?
Obviously, one of the factors is the small window (3x3) that should be made in the loop each time.
Here you go -
Igd = double(Ig);
std2v = colfilt(Igd, [3 3], 'sliding', #std);
mean2v = conv2(Igd,ones(3),'same')/9;
Ig_out = uint8((k*meanTotal)./(std2v + b).*abs(Igd-cal*mean2v) + mean2v.^a);
This will change the boundary elements too, which if not desired could be set back to the original ones with few additional steps, like so -
Ig_out(:,[1 end]) = Ig(:,[1 end])
Ig_out([1 end],:) = Ig([1 end],:)
I am trying to convert this PHP validation code to ColdFusion. However, I cannot get my CF version to correctly validate a VIN. I am hoping someone can shed some light on what I'm missing.
<cfscript>
function isVIN(v) {
var i = "";
var d = "";
var checkdigit = "";
var sum = 0;
var weights = [8, 7, 6, 5, 4, 3, 2, 10, 0, 9, 8, 7, 6, 5, 4, 3, 2];
var transliterations = {
a = 1,
b = 2,
c = 3,
d = 4,
e = 5,
f = 6,
g = 7,
h = 8,
j = 1,
k = 2,
l = 3,
m = 4,
n = 5,
p = 7,
r = 9,
s = 2,
t = 3,
u = 4,
v = 5,
w = 6,
x = 7,
y = 8,
z = 9
};
if (! REFindNoCase("^([\w]{3})[A-Z]{2}\d{2}([A-Z]{1}|\d{1})([\d{1}|X{1})([A-Z]+\d+|\d+[A-Z]+)\d{5}$", ARGUMENTS.v)) {
return false;
}
if (Len(ARGUMENTS.v) != 17) {
return false;
}
for (i = 1; i <= Len(ARGUMENTS.v); i++) {
d = Mid(ARGUMENTS.v, i, 1);
if (! isNumeric(d)) {
sum += transliterations[d] * weights[i];
} else {
sum += d * weights[i];
}
}
checkdigit = sum % 11;
if (checkdigit == 10) {
checkdigit = "x";
}
if (checkdigit == Mid(ARGUMENTS.v,8,1)) {
return true;
}
return false;
}
</cfscript>
(There is a VIN validation function at CFLib.org, but it doesn't work either).
Your function has two issues.
First, the regex is incorrect. Here's a simplified working version:
^[A-Z\d]{3}[A-Z]{2}\d{2}[A-Z\d][\dX](?:[A-Z]+\d+|\d+[A-Z]+)\d{5}$
Note: As per Adam's answer there's a simpler pattern than this.
Second, in your checkdigit comparison the Mid is one out - it seems the 8 should be a 9.
(Presumably this is a language conversion issue due to PHP being 0-indexed whilst CFML is 1-indexed.)
With both of these fixed, the modified function returns true for the VIN WAUBA24B3XN104537 (which is the only sample VIN I could find in a quick search).
Actually the regex is slightly wrong still. I think #PeterBoughton fixed the syntax, but it wasn't actually valid for the task at hand.
Here's the revised section of code, with suitable comments:
var vinRegex = "(?x) ## allow comments
^ ## from the start of the string
## see http://en.wikipedia.org/wiki/Vehicle_Identification_Number for VIN spec
[A-Z\d]{3} ## World Manufacturer Identifier (WMI)
[A-Z\d]{5} ## Vehicle decription section (VDS)
[\dX] ## Check digit
[A-Z\d] ## Model year
[A-Z\d] ## Plant
\d{6} ## Sequence
$ ## to the end of the string
";
if (! REFindNoCase(vinRegex, arguments.v)) {
return false;
}
This could be dramatically simplified to just this:
^[A-Z\d]{8}[\dX][A-Z\d]{2}\d{6}$
Using either of these also removes the requirement for the length check, as the regex will enforce that too.
Test code for this modification:
for (vin in [
"1GNDM19ZXRB170064",
"1FAFP40634F172825"
]){
writeOutput("#vin#: #isVin(vin)#<br />");
}
I'm gonna update CFLib with the verbose version, as it's easier to understand what's going on, and marry-up to the spec.
It is known that MATLAB works slow with for loop. I have tried to vectorize the following code without success. Perhaps I am wrong with the implementation.
for I = NS2:-1:1
A = 0;
for J=1:8
A = A + KS2(J,I)*FA(J);
end
S2 = S2 + ( SS2(1,I)*sin(A) + SS2(2,I)*cos(A) );
end
where:
FA = matrix 1x8
KS2 = matrix 8x25
SS2 = matrix 2x25
A = scalar
S2 = scalar
I try to improve it in this way:
A = 0;
J = 1:8;
for I = NS2:-1:1
A = FA(1,J)*KS2(J,I);
S2 = S2 + ( SS2(1,I)*sin(A) + SS2(2,I)*cos(A) );
end
However, the runtime for this improvement is similar to the original code.
Try this instead (no loops):
A = (FA*KS2).'; %'# A is now 25-by-1
S2 = SS2(1,:)*sin(A) + SS2(2,:)*cos(A);