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# rrlangly

Member Since 05 Mar 2012
Offline Last Active Apr 21 2016 12:15 AM

### 3d shortest path algorithm

21 April 2016 - 12:07 AM

I'm familiar with A* and have worked it on a 2D problem (cars). I am now looking to learn about shortest path problems for a 3D space (working with flying a drone) and was hoping someone could tell me what algorithms (simplest) to look at.

I'm wanting to take off, fly to an ordered number of way points, and return.

thanks,

### math required for Adaline neural network

20 January 2013 - 04:37 PM

Hi,

I've implemented an adaline neural network by looking at example code, but at times it seems buggy and I really need to understand it better to know exactly what my problem is.

Eventually, I'd like to implement other types of networks, but just to start off with and for adalines only ...

What is the minimim math I need to understand this. My current plan is to buy some math books just to cover what I need and dig in.

Any suggestions/recommendations much appreciated.

### trying to plot linear equation

30 July 2012 - 08:07 PM

I believe this code is generating random data points and plotting based on a linear equation, but I'm not sure how to solve this equation manually to check how points are lining up.

Can anyone point me to something so I can understand how to plot points from this equation?

```			x = ((double)rand()/(double)RAND_MAX) * 2.0 - 1.0;
y = ((double)rand()/(double)RAND_MAX) * 2.0 - 1.0;

y1 = (-5 * x - 2) / -4;
```

### find direction from point A to point B

16 April 2012 - 04:47 PM

I'm not very good at math, but heres what I'd like to do ...

I have an object located on a 2d grid, so I know its current point. I get direction by moving the point a short distance in the forward direction so I know where its pointing. My target location is a secondary point. My goal is to find direction to the next point.

So basically, I just want to turn my object to the correct angle and move it to a specified location.

Can anyone help w/ how this is done?

### help calculating G cost of A* algorithm

12 March 2012 - 03:47 PM

I am trying to implement the A* algorithm for pathfinding and having trouble understanding G cost.

Here is a small grid area of node id's from a larger grid.
```52   53   54   55   56
102  103  104  105  106
152  153  154  155  156
202  203  204  205  206
252  253  254  255  256
```

Horizontal and vertical moves increment 10, diagonal increments 14. I am followig this tutorial ... http://www.policyalm...tarTutorial.htm

Node 103 is my starting node. So the lowest F score above takes me to node 154 from 103. I have calculated the G cost as follows from node 153.
```14   10   14
10	  10
14   10   14
```
Next iterations F score gives me node 205, so I then calculate G cost from node 205 and I get the following:
```28  24  28
24	 24
28  24  28
```
And one more iterations F score gives me node 256, so I calculate G cost from node 256:
```42  38  42
38	 38
42  38  42
```
Am I calculating G cost correctly?

Something I don't understand is after I choose the lowest F score, the G cost of 4 nodes is always the same and therefore I can't choose a lowest G cost at this point.

Any help much appreciated.

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