I am having trouble with implementing a brainfuck assembler for codegolf.se. I managed to load a string in to memory find its length cat it out, print strings n times etc, but I cant seem to load just the non lower case numbers into memory. So lets take the following loop which performs some wizardry. (Hash marks are debugging markers.)
#,#[>#<[<]<<#+#>>>[>]#,#]<[<]
It starts at pointer 512 and writes the string as ascii values to spots after 512
Now if (for whatever reason) I wish to strip out lowercase characters, it will look like this in psuedo BF.
#,#[>#<[<]<<#+#>>>[>]#do{,(takes input and assigns it)}
while(input>=96/*Go arbitrarily to the right for this implementation but
make sure that the first non-lowercase number is stored at the index*/)#
//Also be sure to zero out any temporary cells used
<[<]
Now my question is, how do I implement such a while loop while only using spaces to the right of 512 as storage AND clearing them out later.
For those curious, this is the problem I wish to solve in branfuck.
Your code can be simplified to
,[[<]<+>>[>],]<[<]
(the <<+>> is probably a result of using online compiler that forgets cell 255)
and repeated, to produce the outputting operation:
>.[[<]<->>[>]<.>]<[<]
If you want to use only the empty cells in your way, you can do it. But you will need to establish some protocol of your own for defining the next cell, like saving every data cell with the following cell stating the distance to the next one, as:
[..., 104, 5, x, x, x, x, 108, 3, x, x, 102, 2...]
[..., 104 , 5 , x, x, x, x, 108 , 3 , x, x, 102 , 2 ...]
data pointer data pointer data pointer
when x is some arbitrary, none-zero value (otherwise you would use it). This implementation would be kind-of a linked list, but notice it would be space and code expensive.
Zeroing down cells, or as you call it cleaning them, can be done the same way you did the [<] - by using [-]. this will decrease the cell's value until it reaches 0 - and then will loop-out. You can iterate the string down when you are in its end - and go back while cleaning every cell until you hit the beginning (0 or other reserved number you put there).
Related
I am trying to find a (SoP)-expression using the embedded K-map. I have a box of size 4x4 which is a permitted use however I am having a hard time understanding how I could implement it.
To me the 4x4 box represents that the output is always 1 independet on any of the variables. Then I'd like to use the 2x4 box to the right and produce:
1 OR (Qc AND !Qd), but this does not produce the correct result.
I can see several alternative ways to produce the correct result. My questions are specifically:
Why can't I use the 4x4 box, or perhaps, how do I represent it correctly?
How do I know when I can represent parts of the output as a 4x4 box?
Perhaps Im missing something more fundamental.
Thx in advance.
The point of placing rectangles in a K-map is to eliminate variables from an expression. When the result of a rectangle is the same for the variable values X and X', then the variable X is not needed and can be removed. You do this by extending an existing rectangle by doubling the size and eliminating exactly one variable, where every other variable stays the same. For the common/normal K-map with four variables this works with every such rectangle because in a way the columns/rows are labelled/positioned. See the following example:
The rectangle has eliminated the variables A and B, one variable at a time when the size of the rectangle has been extended/doubled. This results in the function F(A,B,C,D) = C'D'. But check the following K-map of four variables:
Notice that the columns for the D variable has been changed (resulting in a different function overall). When you try to extend the red rectangle to catch the other two 1 values as well, you are eliminating two variables at the same time (B and D). As you cannot grow the rectangle anymore, you are left with two rectangles, resulting in the function F(A,B,C,D) = BC'D' + B'C'D (which can be simplified to C' * (BD' + B'D)).
The practice in placing rectangles in the K-map isn't just placing the biggest rectangle possible, but to eliminate variables in the right way. To answer your questions, you can always start with the smallest rectangle and extend/double its size to eliminate one variable. See the following example:
The green rectangle grows in these steps:
Start with A'BC'D'E
Eliminate the (only) variable A by growing "down", resulting in BC'D'E
Eliminate the (only) variable D by growing "right", resulting in BC'E.
But now, the rectangle cannot grow/double its size anymore because that would eliminate the variable E, but also somehow eliminate the variable C. You cannot eliminate the variable E, because you have 0 values to the left of the green rectangle and 1 values to the right of the green rectangle (all in the left half of the K-map, where you have the value C'). The only way to increase/grow the rectangle is to get the "don't care" values to eliminate the B variable (not shown here).
The overall function for this K-map would be F(A,B,C,D,E) = C'E + DE' + CD' (from three 2x4 rectangles).
I am new to LabVIEW and I am trying to read a code written in LabVIEW. The block diagram is this:
This is the program to input x and y functions into the voltage input. It is meant to give an input voltage in different forms (sine, heartshape , etc.) into the fast-steering mirror or galvano mirror x and y axises.
x and y function controls are for inputting a formula for a function, and then we use "evaluation single value" function to input into a daq assistant.
I understand that { 2*(|-Mpi|)/N }*i + -Mpi*pi goes into the x value. However, I dont understand why we use this kind of formula. Why we need to assign a negative value and then do the absolute value of -M*pi. Also, I don`t understand why we need to divide to N and then multiply by i. And finally, why need to add -Mpi again? If you provide any hints about this I would really appreciate it.
This is just a complicated way to write the code/formula. Given what the code looks like (unnecessary wire bends, duplicate loop-input-tunnels, hidden wires, unnecessary coercion dots, failure to use appropriate built-in 'negate' function) not much care has been given in writing it. So while it probably yields the correct results you should not expect it to do so in the most readable way.
To answer you specific questions:
Why we need to assign a negative value and then do the absolute value
We don't. We can just move the negation immediately before the last addition or change that to a subtraction:
{ 2*(|Mpi|)/N }*i - Mpi*pi
And as #yair pointed out: We are not assigning a value here, we are basically flipping the sign of whatever value the user entered.
Why we need to divide to N and then multiply by i
This gives you a fraction between 0 and 1, no matter how many steps you do in your for-loop. Think of N as a sampling rate. I.e. your mirrors will always do the same movement, but a larger N just produces more steps in between.
Why need to add -Mpi again
I would strongly assume this is some kind of quick-and-dirty workaround for a bug that has not been fixed properly. Looking at the code it seems this +Mpi*pi has been added later on in the development process. And while I don't know what the expected values are I would believe that multiplying only one of the summands by Pi is probably wrong.
I have a function returning a setof records. This can be seen in this picture
.
I have a range of boards of length 2.8m thru to 4.9m (ln28 thru ln49 respectively) they have characteristics that set bits as seen in bincodes (9,2049,4097 etc.) For each given board length, I need to sum the number of boards for each bincode. EG in this case ln28 (bincode 4097) would = 3+17+14 = 34. Where you see brdsource = 128 series is where I intend to store these values, so for row brdsource 128, bincodes 4097, I want to store 34 in ln28.
You will see that I have 0's in ln28 values for all brdsource = 128. I have generated extra records as part of my setof records, and am trying to use a multidimensional array to add the values and keep track of them as seen above with array - Summary[boardlength 0-8][bincode 0-4].
Question 1 - I see that if I add 1 (for argument sake, it can be any number) to an array location, it returns a null value (no error, just nothing in table cell). However if I first set the array location to 0, then add 1, it works perfectly. How can an array defined as type integer hold a null value?
Question 2 - How do I add my respective record (call it rc) board length count to the array. IE I want to do something like this
if (rc.bincode = 4097) then Summary[0][2] := Summary[0][2] + rc.ln28;
and then later, on, when injecting this into my table (during brdsource = 128 phase) :
if (rc.bincode = 4097) then rc.ln28 := Summary[0][2];
Of course I may be going about this in a completely unorthodox way (though to me SQL is just plain unorthodox, sigh). I have made attempts to sum all previous records based on the required conditions (eg using a case(when...end) statement, but I proved what I already suspected, ie that each returned record is simply a single row of data. There is just no means of accessing data in the previous record lines as returned by the functions FOR LOOP...END LOOP.
A final note is that everything discussed here is occurring inside the function. I am not attempting to add records etc. to data returned by the function.
I am using PostgreSQL 9.2.9, compiled by Visual C++ build 1600, 64-bit. And yes I am aware this is an older version.
I am writing a code in FORTRAN to calculate the position of the planets. I need to solve Kepler's equation using newtons numerical method and I am having trouble with my loop. The code is shown below. I can compile it with no error messages, but it wont run. It just gets stuck in a forever loop. I want the loop to run until E(i) and the following result are equal. Any help would be greatly appreciated.
do while (E(i)/=E(i+1))
E(1)=M
E(i+1)=E(i)-((M-E(i)+(p*sin(E(i))))/((p*cos(E(i)))-1))
end do
Also, how do i define the variable 'E' at the beginning of my program. I currently have this but the '11' is only because I originally had my loop run 10 times. If I don't specify the number of times I want the loop to run, how do i define the variable?
double precision :: E(11)
I did not check if your convergence implementation is correct, but you definitely do not want to check for exact equality. You must allow for some inexactness, because floating point calculations are inexact
(abs(E(i)-E(i+1))<eps)
where eps is some small number.
As #agentp suggests you don't change i, so you always work with 2 values E(i) and E(i+1) (i being whatever you set it before the loop). You do not use any other elements of your array.
For the array which can have any length, depending on your need, you could theoretically use
double precision, allocatable :: E(:)
but you probably do not want to use an array at all and you just want two scalar values
double precision :: E1, E2
E1 = M
do
E2 = E1 - ((M-E1+(p*sin(E1))) / ((p*cos(E1))-1))
if (abs(E1-E2) < eps) exit
E1 = E2
end do
Note that the kind notation (real(....)) is preferable in new code instead of the old double precision.
So, this should be an easy question for anyone who has used FORTH before, but I am a newbie trying to learn how to code this language (and this is a lot different than C++).
Anyways, I'm just trying to create a variable in FORTH called "Height" and I want a user to be able to input a value for "Height" whenever a certain word "setHeight" is called. However, everything I try seems to be failing because I don't know how to set up the variable nor how to grab user input and put it in the variable.
VARIABLE Height 5 ALLOT
: setHeight 5 ACCEPT ATOI CR ;
I hope this is an easy problem to fix, and any help would be greatly appreciated.
Thank you in advance.
Take a look at Rosettacode input/output examples for string or number input in FORTH:
String Input
: INPUT$ ( n -- addr n )
PAD SWAP ACCEPT
PAD SWAP ;
Number Input
: INPUT# ( -- u true | false )
0. 16 INPUT$ DUP >R
>NUMBER NIP NIP
R> <> DUP 0= IF NIP THEN ;
A big point to remember for your self-edification -- C++ is heavily typecasted, Forth is the complete opposite. Do you want Height to be a string, an integer, or a float, and is it signed or unsigned? Each has its own use cases. Whatever you choose, you must interact with the Height variable with the type you choose kept in mind. Think about what your bits mean every time.
Judging by your ATOI call, I assume you want the value of Height as an integer. A 5 byte integer is unusual, though, so I'm still not certain. But here goes with that assumption:
VARIABLE Height 1 CELLS ALLOT
VARIABLE StrBuffer 7 ALLOT
: setHeight ( -- )
StrBuffer 8 ACCEPT
DECIMAL ATOI Height ! ;
The CELLS call makes sure you're creating a variable with the number of bits your CPU prefers. The DECIMAL call makes sure you didn't change to HEX somewhere along the way before your ATOI.
Creating the StrBuffer variable is one of numerous ways to get a scratch space for strings. Assuming your CELL is 16-bit, you will need a maximum of 7 characters for a zero-terminated 16-bit signed integer -- for example, "-32767\0". Some implementations have PAD, which could be used instead of creating your own buffer. Another common word is SCRATCH, but I don't think it works the way we want.
If you stick with creating your own string buffer space, which I personally like because you know exactly how much space you got, then consider creating one large buffer for all your words' string handling needs. For example:
VARIABLE StrBuffer 201 ALLOT
This also keeps you from having to make the 16-bit CELL assumption, as 200 characters easily accommodates a 64-bit signed integer, in case that's your implementation's CELL size now or some day down the road.