Eval()vs.substitute()
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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