Thread: why can't my perceptron learn correctly?

1. Your indentation is terrible. (You don't have any!)
2. You use out without initializing it.
3. You check to see if wantedout is what you want, before you ever do anything with it.


Quzah.

Indent style - Wikipedia, the free encyclopedia

srry, but i initialise out... and i do chek wantedout... sorry about the indentitation

No you don't, and no you didn't. Here's your code, indented:

Code:

#include <stdio.h>
#define LR 0.1
int wantedout;
int out;    <--- not initialized
int input1=0;
int input2=1;
long weight1=50;
long weight2=50;
int error;
educate_net()
{
    out  = ((input1*weight1) + (input2*weight2));
    error = out - wantedout;
    weight1 = weight1 - (error*LR);   
    weight2 = weight2 - (error*LR);
}
int main(){
    printf("wanted output:");
    while(1==1){
        scanf("%d", &wantedout);
        while(wantedout != out){  <--- checking the value before...
            educate_net();        <--- ...you actually modify them
            printf("%d\n", out);
        }
    }
    return 0;
}

Quzah.

Originally Posted by quzah

No you don't, and no you didn't. Here's your code, indented:

Code:

#include <stdio.h>
#define LR 0.1
int wantedout;
int out;    <--- not initialized
int input1=0;
int input2=1;
long weight1=50;
long weight2=50;
int error;
educate_net()
{
    out  = ((input1*weight1) + (input2*weight2));
    error = out - wantedout;
    weight1 = weight1 - (error*LR);   
    weight2 = weight2 - (error*LR);
}
int main(){
    printf("wanted output:");
    while(1==1){
        scanf("%d", &wantedout);
        while(wantedout != out){  <--- checking the value before...
            educate_net();        <--- ...you actually modify them
            printf("%d\n", out);
        }
    }
    return 0;
}

Quzah.

ok, but, do i need to in. out when it will be calculated?

Pay a little more attention to the red highlighted parts.

Originally Posted by yann

ok, but, do i need to in. out when it will be calculated?

Technically, gcc and I think probably most compilers will initialize a global to 0 for you, but that is not guaranteed by the standard, so you should not assume that a variable you didn't initialize has any particular value.

In other words, out could be any number initially. What if wantedout == out? The user sets wantedout, but there is no way to say for sure what out is the first time.

Your outer loop retains the old values however, so after giving you the right results for the first loop, it breaks after that. I don't know if that's intentional. I'd guess probably not, but then I don't know what you're really trying to do with your program, so who knows?

Quzah.

Originally Posted by MK27

Technically, gcc and I think probably most compilers will initialize a global to 0 for you, but that is not guaranteed by the standard, so you should not assume that a variable you didn't initialize has any particular value.

Actually, I think that is guaranteed by the standard. Regardless, it's not something you should rely on (especially as a beginning programmer).

Originally Posted by dwks

Actually, I think that is guaranteed by the standard. Regardless, it's not something you should rely on (especially as a beginning programmer).

Not if it isn't static it isn't.


Quzah.

Originally Posted by quzah

Not if it isn't static it isn't.


Quzah.

Yes - global AND static variables are initialized to zero. Or rather, everything that gets put in .bss normally.

Originally Posted by IceDane

Yes - global AND static variables are initialized to zero. Or rather, everything that gets put in .bss normally.

No. Static yes, global no. (Unless you're saying a static global, but then that's covered under the heading of 'static' already.) Feel free to prove me wrong, but I'm not seeing where it guarantees that global variables are guaranteed default initialization. I could be just too tired to see/find it, but I'm not seeing it.


Quzah.

Originally Posted by abachler

another little piece of advice is that perceptrons generally need either fixed or floating point weights, inputs and outputs. integers just won't do.

Oh god please no don't do this...