Question 176339 in PHP Question posted in
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What’s wrong with my PHP algo func & how do I fix it?

I’m trying to understand a specific pattern where each term is the sum of the previous term and the current Fibonacci number. The pattern follows this sequence:

1
1 + 1 = 2 
1 + 1 + 2 = 4 
1 + 1 + 2 + 3 = 7 
1 + 1 + 2 + 3 + 5 = 12

And so on

I would like to create a function in PHP that generates this pattern. I have attempted to modify a standard Fibonacci function, but the results are not as expected. Here’s the code I’ve tried so far:

function getResult($n) {
  $result = [];
  $previous = 0;
  $current = 1;

  for ($i = 1; $i <= $n; $i++) {

    $result[] = $current;
    
    $previous = $current; 
    
    $next = $previous + $current;
    
    $current = $next;
  
    
  }

  return $result;
}
Tags:

2

Answers


  1. 0

    Put $previous = $current; after $next = $previous + $current;

    Live JavaScript snippet just to illustrate the result:

    function getResult ($n) {
  let $result = [];
  let $sum = 0;
  let $previous = 0;
  let $current = 1;
  let $next;

  for (let $i = 1; $i <= $n; $i++) {
    $result.push($current);
    $sum += $current;
    $next = $previous + $current;
    $previous = $current;
    $current = $next;
  }

  return { $result, $sum };
}

for (let $n = 1; $n <= 10; $n++) {
  let { $result, $sum } = getResult($n);
  console.log(`${$result.join(' + ')} = ${$sum}`);
}

    Update: Or did you mean you want to generate the sequence 1 2 4 7 12 20 33?

    Then this is basically Sn = Fn+2-1:

    function getResult ($n) {
  let $result = [];
  let $previous = 1;
  let $current = 2;
  let $next;

  for (let $i = 1; $i <= $n; $i++) {
    $result.push($current - 1);
    $next = $previous + $current;
    $previous = $current;
    $current = $next;
  }

  return $result;
}

for (let $n = 1; $n <= 10; $n++) {
  console.log(getResult($n).join(', '));
}
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  2. 0

    For Fibonacci Sequent (0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144…..), you may use the following PHP code to get:

    <?php  

function getresult($x) {
  $num = 0;  
  $n1 = 0;  
  $n2 = 1;  
  $n3 = 0;  
  $n4 = 0; 

if ($x==0) { return $n1; }
if ($x==1) { return $n2; }


while ($num < ($x-1) )  {  
    $n3 = $n2 + $n1;  
    $n4=$n3;
    $n1 = $n2;  
    $n2 = $n3;  
    $num = $num + 1;  
}

if ($x>=2){
  return $n4;   
  }
}   

//How to use:
//echo getresult(2);

?>

    So, for your case which you want to get the sum of the previous terms and the current Fibonacci number (1 2 4 7 12 20 33 54 88 143 …), you can use the following:

    <?php  

function getresult($x) {
  $num = 0;  
  $n1 = 0;  
  $n2 = 1;  
  $n3=0;  
  $n4=0; 

if ($x==0) { return $n1; }
if ($x==1) { return $n2; }


while ($num < ($x-1) )  {  
    $n3 = $n2 + $n1;  
    $n4=$n3;
    $n1 = $n2;  
    $n2 = $n3;  
    $num = $num + 1;  
}

if ($x>=2){
  return $n4;   
  }


}   


// show Fibonacci series; 
for($local=0; $local < 10; $local++) {
       echo getresult($local) . ' ' ;       
}


function getresult2($fi)
{
    $local2=0;
    
  for($local=0; $local < $fi; $local++) {
       $local2 +=getresult($local) ;        
  }
    return $local2; 
    
}


echo "nn";

$fi=10;
for($local=2; $local < $fi+2; $local++) {
       echo getresult2($local) . ' ' ;      
}


?>

    See DEMO

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