How can i get from equation one variable as a function of other variables? For example we have A*x^2 + R1*V*x + R2*v + z = 0; and i must get result V(R1,R2) = -(A*x^2 + z)/ (R1*x+R2). This is ofcourse simple example.
Investigate Solve and Reduce. This is, of course, a simple answer but should get you started.
Related
I need example of solving non-linear euations system with octave "sqp" function, but not found anything like it (yes, maybe my knowledge of math is too bad for documentation :-) )
I have system of next 2 equations :
tan(x*y+0.3)-x^2 = 0
x^2+2*y^2-1 = 0
How can I use "sqp" for it?
Found example on http://realsuddenlike.wordpress.com/2008/07/22/nonlinear-minimization-in-octave-sequential-quadratic-programming/
For
f(x,y)=x^2+y^2.
Work's next code
function out=obj_fcn1(x)
x=x(:);
out=x’*x;
end
[x_f,j_f]=sqp(x_0,#(x)obj_fcn1(x),[],#(x)bndfcn(x));
My system can be adapted
f(x_1, ..., x_n) = f_1(x1, ..., x_n)^2 + ... + f_n(x1, ..., x_n)^2 = 0
Please excuse the beginner question. I couldn't find an appropriate answer in any Mathematica tutorial.
I am confused why a definition as a function or a definition in terms of a simple replacement produce different results. Consider this example (Mathematica 9 code):
In[397]:= ClearAll["Global`*"]
In[398]:= Test := 3 c^2 + d^4
In[399]:= v[f_] := D[f, c]
In[400]:= v[Test]
Out[400]= 6 c
The first definition of this simple derivative function "v" acting on a variable is fine. Defining a replacement Test = ... to replace the variable produces the expected result (It derives 3c^2+d^4 with respect to c and answers 6c).
However if I define a function instead of a simple replacement this does not work:
In[401]:= TestFunction[a_, b_] := 3 a^2 + b^4
In[403]:= vFunction[f_[a_, b_]] := D[f[a, b], a]
In[405]:= vFunction[TestFunction[a, b]]
Out[405]= \!\(
\*SubscriptBox[\(\[PartialD]\), \(3\
\*SuperscriptBox[\(a\), \(2\)]\)]\((3\
\*SuperscriptBox[\(a\), \(2\)] +
\*SuperscriptBox[\(b\), \(4\)])\)\)
Why is that? I am risking to look like a moron here, but please enlighten me!
For your convenience, I uploaded a copy of my workbook here
Thanks a lot,
Michael
Do this instead
vFunction[f_,a_,b_]:=D[f[a,b],a];
and when you need derivatives simply use vFunction[TestFunction,a,b] to get it.
When you write down f[x], it means the evaluated value of f with argument value x. So, f[x] is technically not a function anymore. What you want as the argument of vFunction[] is the function TestFunction, not the evaluated value.
I am not a F
lash expert.
I have a FLA file of a game coded in ActionScript 3.
The game has a string inside, "www.mywebsite.com".
I want that when someone opens this FLA and searches for ".com" or "mywebsite.com" to find nothing. So I have decided to encode that string somehow. But I never coded in Flash, so I have no idea what to start with and Google isn't helping.
Basically all I want to do is replace this line:
var url1 = 'www.mywebsite.com';
With something like this and be functional.
var url1 = base64_decode('asdahwiyadwaeawr==');
Even a XOR or other simple string manipulation algorithm would be good.
What options do I have without importing any non-standard libraries into Flash?
Anyone looking through your code at something like var url = BlaBla_decode("cvxcvxc"); can simply replace it with var url = "www.HisWebsite.com...
So I guess you're supposing no one will be going through your script line by line but instead search for ".com" (Which would make him a really lazy jerk)!
A simple solution is to come up with a function that would return "www.MyWebsite.com" without writing it;
Something like:
var url:String = youAreStupid();
function youAreStupid():String
{
return String(f(22) + f(22) + f(22) + "extra.extra" + f(12) + f(24) + f(22) + f(4) + f(1) + f(18) + f(8) + f(19) + f(4) + "extra.extra" + f(2) + f(14) + f(12)).replace(/extra/g, "");
}
function f(n:Number):String
{
return String.fromCharCode("a".charCodeAt(0) + n);
}
I can't but say this would be lame way to protect your document, and I suggest you keep a comment at the top of your Script (something clearly visible) : // You won't find it YOU ARE STUPID
Now if he's smart enough to search for youAreStupid, that means he's entitled to change it :p
Of course there's also the simpler:
String("-Ow-Mw-Gw-!.-Ym-Oy-Uw-Ae-Rb-Es-Si-Ot-Se-T.-Uc-Po-Im-D").replace(/-./g, "");
but that's no fun!!!
This code is not java code, and I'm not getting any answer from ActionScript developers. So I tagged it with java, but Action Script is similar to java and this an OOP question.
I'm using Grid Data and I want to accomplish this following task:
Method 1: I want to multiply each row Row1num1 * Row1num2 and so on,
var Row1num1:String;
var Row2num2:String;
var Row2num1:String;
var Row2num2:String;
var Row3num1:String;
var Row3num2:String;
var event1:Object={num1:Row1num1,num2:Row1num2};
var event2:Object={num1:Row2num1,num2:Row2num2};
var event3:Object={num1:Row3num1,num2:Row3num2};
then add them to a dataGrid
dataGrid.columns =["num1","num2"];
dataGrid.addItem(event1);
dataGrid.addItem(event2);
dataGrid.addItem(event3);
but by using this method, if I have 20 rows, I will have a lot of variables, obviously it's bad.
method 2: In this method creating Grid Data rows at runtime and multiply them.
//button to add rowGrid
dd.addEventListener(MouseEvent.CLICK,ddd);
var numm:String="34";
function ddd(evt:MouseEvent):void
{
var event4:Object={num1:Rownum1,num2:Rownum2};
dataGrid.addItem(event4);
}
but when I use this method, I have a hard time accessing each row data and multiply them.
This example because I'm creating GPA calculator and I want to take each row credit Hours and multiply them with the scale value at the same row, first method is bad because there's not abstraction .
The second method what I'm hoping to work ,because I want user to add row depend on their number of courses.
I hope my English is not bad.
I hope my question don't get vote down, and by reading this question can you determine what I'm missing so I can learn it .
And is there any tutorial I can use to solve my problem?
I'm just addressing your first method for now, but it almost seems at though you want an array of some sort.
Here's a link on how to use Actionscript arrays.
If you need more dimensions, you can make an array of arrays. This will help you cut down on the number of variables.
I hope I correctly understood your question. I'll give it a go either way...
So, one of the best things about actionscript in comparison to most other strongly-typed Object-Oriented languages is how easy reflection is (probably thanks to its javascript origins).
That being said, what you can do is simply create an array using a "for" loop. What I am assuming is that the variables row1Num1 row2Num2 and so on already exist in your class. Otherwise, obviously it would be much more efficient to store them in an array and simply read from it into a new array. Anyhow, the code should look something like this:
method 1:
var eventsArr:Array = [];
for(var i:int = 1; this["row" + i + "Num1"] != undefined /*or i<=length*/; i++){
eventsArr.push({num1:this["row" + i + "Num1"], num2:this["row" + i + "Num2"]});
}
for(var j:int = 0; j < eventsArr.length; j++){
dataGrid.addItem(eventsArr[j]);
}
method 2:
dd.addEventListener(MouseEvent.CLICK,ddd);
var numm:String="34"; //I am assuming this refers to the row number you wanted to add.
function ddd(evt:MouseEvent):void
{
var event4:Object={num1:this["row" + numm + "Num1"],num2:this["row" + numm + "Num2"]};
eventsArr.push(event4);
dataGrid.addItem(event4);
}
Hope that helps.
I've been looking around and I have not been able to find anything that has worked for me. I'm starting to learn more Lua and to start off I'm making a simple calculator. I was able to get each individual operation onto separate programs, but when I try to combine them I just can't get it to work. My script as it is now is
require "io"
require "operations.lua"
do
print ("Please enter the first number in your problem.")
x = io.read()
print ("Please enter the second number in your problem.")
y = io.read()
print ("Please choose the operation you wish to perform.")
print ("Use 1 for addition, 2 for subtraction, 3 for multiplication, and 4 for division.")
op = io.read()
op = 1 then
function addition
op = 2 then
function subtraction
op = 3 then
function multiplication
op = 4 then
function division
print (answer)
io.read()
end
and my operations.lua script is
function addition
return answer = x+y
end
function subtraction
return answer = x-y
end
function multiplication
return answer = x*y
end
function division
return answer = x/y
end
I've tried using
if op = 1 then
answer = x+y
print(answer)
if op = 2 then
answer = x-y
print(answer)
and I did that completing each operation. But it doesn't work. I can't even get the error code that it's returning because it closes so fast. What should I do?
In your example, make these changes: You require operations.lua without the extension. Include parameters in your operations function definitions. Return the operation expression directly versus returning a statement like answer = x+y.
All together:
Code for operations.lua
function addition(x,y)
return x + y
end
--more functions go here...
function division(x,y)
return x / y
end
Code for your hosting Lua script:
require "operations"
result = addition(5,7)
print(result)
result = division(9,3)
print(result)
Once you get that working, try re-adding your io logic.
Keep in mind that as it's coded, your functions will be defined globally. To avoid polluting the global table, consider defining operations.lua as a module. Take a look at the lua-users.org Modules Tutorial.
The right if-then-else syntax:
if op==1 then
answer = a+b
elseif op==2 then
answer = a*b
end
print(answer)
After: please check the correct function-declaration syntax.
After: return answer=x+y is incorrect. If you want set answer's value, set without return. If you want return the sum, please use return x+y.
And I think you should check Programming in Lua.
First of all, learn to use the command line so you can see the errors (on Windows that would be cmd.exe).
Second, change the second line to require("operations"). The way you did it the interpreter expects a directory operations with an underlying script lua.lua.