I was wondering if its possible to directly compare 2 vectors with eachother instead of just looking at them bit by bit.
For example:
entity Comparator is
port(a,b in: std_logic_vector (2 downto 0);
out1, out2 out: std_logic);
end Comparator;
architecture behavioural of Comparator1 is
begin
if a = b then
out1 <= '1'
else if /= then
out2 <= '1'
end if;
end behaviour;
Is this possible?
The answer is yes, you can compare two array types of the same type and subtype indication directly.
However your example code isn't valid.
The result of the expression a=b is boolean. You convert that to std_logic by assigning out1 and out2. An if statement in this context has to be in a process statement. Also you don't need two outputs:
architecture foo of Comparator1 is
begin
UNLABELED:
process (a,b)
begin
if a = b then
out1 <= '1';
else
out1 <= '0';
end if;
end process;
end architecture;
Alternative a concurrent signal assignment statement, a conditional signal assignment that has an equivalent process to that above:
architecture fum of Comparator1 is
begin
UNLABELED:
out1 <= '1' when a = b else '0';
end architecture;
You can also use to_integer(unsigned(a)) and threat them as integers.
For example:
IF(to_integer(unsigned(a)) < to_integer(unsigned(b))) THEN
Related
I have made a program for obtaining a list of prime numbers in ADA and using the following online compiler:
https://rextester.com/l/ada_online_compiler
My code is the following:
--GNAT 8.3.0
with Ada.Text_IO, Ada.Integer_Text_IO;
use Ada.Text_IO;
procedure prime is
function isPrime(n:in Integer) return Boolean is
begin
for i in 2..n loop
if n mod i=0 then
return False;
end if;
end loop;
return True;
end isPrime;
begin
for i in 1..100 loop
if isPrime(i)=True then
Ada.Text_IO.Put_Line(Integer'Image(i));
end if;
Ada.Text_IO.Put_Line(Integer'Image(i));
end loop;
end prime;
And instead of printing a list of primes it only print 1. I have program the same code in C and no problem at all.
Your for loop in isPrime() checks every value higher than one as "n mod n = 0" which will cause you to return false for every value higher than 1. Change the for loop condition to
for i in 2..(n-1) loop
and work from there
Expanding on Jere's approach, several simple primality tests will simplify the divisibility test in the isPrime loop:
The only even prime, 2, can be handled immediately:
if N = 2 then
return True;
end if;
All remaining even numbers can be eliminated:
if N mod 2 = 0 then
return False;
end if;
This leaves odd numbers in the range 3 .. √N to check:
for i in 3 .. Positive (Sqrt (Float (N))) loop
if N mod i = 0 then
…
end if;
end loop;
It is even better by defining a Prime_Number type containing prime numbers.
subtype Prime_Number is Positive range 2 .. Positive'Last with
Dynamic_Predicate => (for all I in 2 .. (Prime_Number / 2)
=> (Prime_Number mod I) /= 0);
Then, use the code segment below to print out all prime numbers between 2 .. 100 range.
for Index in Positive range 2 .. 100 loop
if Index in Prime_Number then
Put_Line ("Prime number: " & Index'Image);
end if;
end loop;
Please tell me the problem in the code. I have written this code and its not working. Tell me the mistakes or if there is any other and easy method to generate prime numbers till 1000.
declare
i number;
prime number;
j number;
begin
for i in 2 .. 1000 loop
prime := 0;
for j in 2 .. i/2 loop
if mod(i,j)=0 then prime := 1
end if;
end loop;
if prime = 0 then dbms_output.put_line(i||'&');
end if;
end loop;
end;
You already have your answer (missing semicolon), but just for fun:
The i variable declared at the top is not used.
In theory j would be more efficient as a pls_integer (as i is implicitly). Possibly even a simple_integer, but then you'd need to restructure the loop to make i a simple_integer as well, and it's barely worth it for the tiny fraction of a second you might gain, if the compiler hasn't already optimised it.
You might as well exit the inner loop at the first match, rather than checking every single number.
prime would be more readable as a Boolean.
On the subject of readability, it is standard practice to align end loop under its opening loop statement.
I'm not seeing the point of appending & to every line of output.
This gives me:
declare
j pls_integer;
prime boolean;
begin
for i in 2 .. 1000 loop
prime := true;
for j in 2 .. i/2 loop
if mod(i,j) = 0 then
prime := false;
exit;
end if;
end loop;
if prime then
dbms_output.put_line(i);
end if;
end loop;
end;
You have missed one semicolon and try to put set server output on then run it
set serveroutput on
declare
i number;
prime number;
j number;
begin
for i in 2 .. 1000 loop
prime := 0;
for j in 2 .. i/2 loop
if mod(i,j)=0 then prime := 1;
end if;
end loop;
if prime = 0 then dbms_output.put_line(i||'&');
end if;
end loop;
end;
/
I'm trying to use the concept of recursion but using for do loop. However my program cannot do it. For example if I want the output for 4! the answer should be 24 but my output is 12. Can somebody please help me?
program pastYear;
var
n,i:integer;
function calculateFactorial ( A:integer):real;
begin
if A=0 then
calculateFactorial := 1.0
else
for i:= A downto 1 do
begin
j:= A-1;
calculateFactorial:= A*j;
end;
end;
begin
writeln( ' Please enter a number ');
readln ( n);
writeln ( calculateFactorial(n):2:2);
readln;
end.
There are several problems in your code.
First of all it doesn't compile because you are accessing the undefined variable j.
Calculating the factorial using a loop is the iterative way of doing it. You are looking for the recursive way.
What is a recursion? A recursive function calls itself. So in your case calculateFactorial needs a call to itself.
How is the factorial function declared?
In words:
The factorial of n is declared as
1 when n equals 0
the factorial of n-1 multiplied with n when n is greater than 0
So you see the definition of the factorial function is already recursive since it's referring to itself when n is greater than 0.
This can be adopted to Pascal code:
function Factorial(n: integer): integer;
begin
if n = 0 then
Result := 1
else if n > 0 then
Result := Factorial(n - 1) * n;
end;
No we can do a few optimizations:
The factorial function doesn't work with negative numbers. So we change the datatype from integer (which can represent negative numbers) to longword (which can represent only positive numbers).
The largest value that a longword can store is 4294967295 which is twice as big as a longint can store.
Now as we don't need to care about negative numbers we can reduce one if statement.
The result looks like this:
function Factorial(n: longword): longword;
begin
if n = 0 then
Result := 1
else
Result := Factorial(n - 1) * n;
end;
So I have been given an assignment to read in a file put the numbers into two matrices, multiply the matrices, and finally put the output into a .txt file.
I have never used Ada before and I figured it would be a good challenge. I am stuck in trying to determine the bounds for the two separate arrays.
This is what I currently have:
currentSpread := I;
g := Ada.Numerics.Generic_Complex_Elementary_Functions.Sqrt(I);
while J < g loop
if(I mod J = 0) THEN
if(currentSpread > ((I/J - J)/2)) THEN
currentSpread := ((I/J - J)/2);
arrayBounds := J;
end if;
end if;
J := J + 1;
end loop;
The problem I am having is with the sqrt function. I want to find the factors for the best bounds of the matrix multiplication and this was the only way that I thought to implement it.
The error I am getting is:
invalid prefix in selected component "Ada.Numerics.Generic_Complex_Elementary_Functions"
Thanks a lot for any help.
--Update
Full Code as requested:
with Ada.Text_IO;use Ada.Text_IO;
with Ada.Integer_Text_IO;
with Ada.Numerics.Generic_Complex_Elementary_Functions;
with Ada.Numerics.Generic_Elementary_Functions;
with Ada.Numerics.Complex_Elementary_Functions;
with Ada.Numerics.Generic_Complex_Types;
procedure Main is
dataFile : File_Type;
resultFile : File_Type;
value : Integer;
I : Integer := 0;
J : Integer;
currentSpread : Integer;
arrayBounds : Integer;
g : Integer;
begin
Ada.Text_IO.Open(File => dataFile, Mode => Ada.Text_IO.In_File, Name =>"C:\Users\Jeffrey\Desktop\data.txt");
while not End_Of_File(dataFile) loop
Ada.Integer_Text_IO.Get(File => dataFile, Item => value);
Ada.Integer_Text_IO.Put(Item => value);
Ada.Text_IO.New_Line;
I := I + 1;
end loop;
Ada.Integer_Text_IO.Put(I);
I := I/2;
J := 1;
currentSpread := I;
g := Ada.Numerics.Generic_Complex_Elementary_Functions.Sqrt(I);
while J < g loop
if(I mod J = 0) THEN
if(currentSpread > ((I/J - J)/2)) THEN
currentSpread := ((I/J - J)/2);
arrayBounds := J;
end if;
end if;
J := J + 1;
end loop;
declare
type newArray is array(Integer range <>, Integer range<>) of Integer;
X : Integer := J;
Y : Integer := I/J;
Arr1 : newArray(1..Y, 1..X);
Arr2 : newArray(1..X, 1..Y);
finAnswer : newArray(1..X, 1..X);
begin
for z in 1 .. X loop
for k in 1 .. Y loop
Ada.Integer_Text_IO.Get(File => dataFile, Item => value);
Arr1(z, k) := value;
end loop;
end loop;
for z in 1 .. Y loop
for k in 1 .. X loop
Ada.Integer_Text_IO.Get(File => dataFile, Item => value);
Arr2(z, k) := value;
end loop;
end loop;
for l in 1 .. X loop
for m in 1 .. Y loop
for n in 1 .. X loop
finAnswer(l, n) := finAnswer(l, n) + Arr1(l, n)* Arr2(n, m);
end loop;
end loop;
end loop;
end;
Ada.Text_IO.Close(File => dataFile);
end Main;
I am using the square root exclusively to figure out the factors of a number nothing else. How I have it set up now is it will go up to the square root and then it will take the smallest spread of the factors. I do not care about rounding errors or anything else if it isn't a perfect square it can round either way.
Thanks.
Generic_Complex_Elementary_Functions is a generic package. It cannot be used directly. That is why the compiler gives you an error on this line:
Ada.Numerics.Generic_Complex_Elementary_Functions.Sqrt(I);
To use it, you have to instantiate the generic Generic_Complex_Types with the floating-point type you want to use, and then instantiate Generic_Complex_Elementary_Functions with an instance of Generic_Complex_Types. Fortunately, you don't have to go through all that if you're willing to use the built-in type Float; the language provides Ada.Numerics.Complex_Elementary_Functions for you, that uses Float as the floating-point type, or Ada.Numerics.Long_Complex_Elementary_Functions that uses Long_Float if your compiler vendors support it.
However, I don't think you want to use Complex anything. That deals with complex numbers, and I doubt that you want to use those. Use Ada.Numerics.Elementary_Functions (or Long_Elementary_Functions), which deal with real numbers.
Finally, even this isn't going to work:
Ada.Numerics.Elementary_Functions.Sqrt(I)
if I is an integer, because the argument type needs to be a Float. You'll have to use a type conversion.
Ada.Numerics.Elementary_Functions.Sqrt(Float(I))
I need to write recursive function to count amount of odd numbers in the sequence
Here my initial code:
program OddNumbers;
{$APPTYPE CONSOLE}
uses
SysUtils;
function GetOddNumbersAmount(const x: array of integer; count,i:integer):integer;
begin
if((x[i] <> 0) and (x[i] mod 2=0)) then
begin
count:= count + 1;
GetOddNumbersAmount:=count;
end;
i:=i+1;
GetOddNumbersAmount:=GetOddNumbersAmount(x, count, i);
end;
var X: array[1..10] of integer;
i,amount: integer;
begin
writeln('Enter your sequence:');
for i:=1 to 10 do
read(X[i]);
amount:= GetOddNumbersAmount(X, 0, 1);
writeln('Amount of odd numbers: ', amount);
readln;
readln;
end.
When i type the sequence and press "enter", program closed without any errors and i can't see the result.
Also, i think my function isn't correct.
Can someone help with that code?
UPD:
function GetOddNumbersAmount(const x: array of integer; count,i:integer):integer;
begin
if((x[i] <> 0) and (x[i] mod 2<>0)) then
count:= count + 1;
if(i = 10) then
GetOddNumbersAmount:=count
else
GetOddNumbersAmount:=GetOddNumbersAmount(x, count, i+1);
end;
You don't provide an end of recursion, i.e., you always call your function GetOddNumbersAmount again, and your program never terminates. Thus, you get an array index error (or a stack overflow) and your program crashes.
Please note, that every recursion need a case where it terminates, i.e. does not call itself. In your case, it should return if there are no elements in the array left.
In addition, you are counting the even numbers, not the odd ones.
You passed a static array to a dynamic so the index get confused:
Allocat the array with
SetLength(X,10)
allocates an array of 10 integers, indexed 0 to 9.
Dynamic arrays are always integer-indexed, always starting from 0!
SetLength(X,10)
for it:=0 to 9 do begin
X[it]:= random(100);
And second if you know the length a loop has more advantages:
function GetEvenNumbersAmount(const x: array of integer; count,i:integer):integer;
begin
for i:= 0 to length(X)-1 do
if((x[i] <> 0) and (x[i] mod 2=0)) then begin
inc(count);
//write(inttostr(X[i-1])+ ' ') :debug
end;
result:=count;
end;