Difference between revisions of "Eval()vs.substitute()"

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(New page: The aim of this page is to demonstrate the difference between <code> eval() </code> and <code> substitute </code>. Note:PGLabs is an efficient way to check code. $f = Compute(sqrt(3...)
 
m (Changed 2nd "eval" to "substitute")
 
(3 intermediate revisions by 2 users not shown)
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The aim of this page is to demonstrate the difference between <code> eval() </code> and <code> substitute </code>.
+
The aim of this page is to demonstrate the difference between <code>eval()</code> and <code>substitute</code>.
   
 
Note:[[PGLabs]] is an efficient way to check code.
 
Note:[[PGLabs]] is an efficient way to check code.
Line 10: Line 10:
   
 
$f = Compute(sqrt(3x + 1);
 
$f = Compute(sqrt(3x + 1);
$fx = $f->eval(x=>"3");
+
$fx = $f->substitute(x=>"3");
 
displays (3.16228)
 
displays (3.16228)
   
 
The correct answer is a formula (hence the parenthesis)
 
The correct answer is a formula (hence the parenthesis)
   
One of the biggest differences between <code> eval() </code> and <code> substitute </code> is when they are used in conjunction with flags such as <code> reduceConstants </code> and <code> reduceConstantFunctions </code>, which is described in more detail at:[[FormattingCorrectAnswers]]
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One of the biggest differences between <code>eval()</code> and <code>substitute</code> is when they are used in conjunction with flags such as <code>reduceConstants</code> and <code>reduceConstantFunctions</code>, which is described in more detail at:[[FormattingCorrectAnswers:_NumbersAndFormulas]]

Latest revision as of 16:29, 7 July 2011

The aim of this page is to demonstrate the difference between eval() and substitute.

Note:PGLabs is an efficient way to check code.

$f = Compute(sqrt(3x + 1);
$fx = $f->eval(x=>"3");
displays 3.16228

The correct answer is a number.

$f = Compute(sqrt(3x + 1);
$fx = $f->substitute(x=>"3");
displays (3.16228)

The correct answer is a formula (hence the parenthesis)

One of the biggest differences between eval() and substitute is when they are used in conjunction with flags such as reduceConstants and reduceConstantFunctions, which is described in more detail at:FormattingCorrectAnswers:_NumbersAndFormulas