Tested on WW 2.16 and WW 2.17.

An instructor asked me about an issue with the question below from a live assignment with seed 3463 where $c (which should have at most two decimal places) is displayed as -0.780000000000001.

Is such an error type to be expected once in a while?

DOCUMENT();

loadMacros(

"PGstandard.pl",

"MathObjects.pl",

"PGML.pl",

"PGcourse.pl",

);

Context("Numeric");

$showPartialCorrectAnswers = 1;

$a=non_zero_random(-20,20,0.01);

$b=non_zero_random(-20,20,0.01);

$c=non_zero_random(-20,20,0.01);

$mag=sqrt($a**2+$b**2+$c**2);

$smag=sprintf("%.6f",$mag);

@dir=($a/$mag,$b/$mag,$c/$mag);

@sdir=(sprintf("%.6f",$dir[0]),sprintf("%.6f",$dir[1]),sprintf("%.6f",$dir[2]));

TEXT(beginproblem());

BEGIN_PGML

What is the unit vector for the vector [`\langle [$a],[$b],[$c] \rangle`]?

Answer: [`\langle`][__________]{$dir[0]},[__________]{$dir[1]},[__________]{$dir[2]}[`\rangle`]

END_PGML

ENDDOCUMENT();