Difference between revisions of "FormattingDecimals"
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− | # log base 10 |
+ | # log base 10 is log10, logten, |
+ | # ln(x)/ln(10), or log(x)/log(10) |
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$c = sprintf("%0.3f", ln($a)/ln(10) ); # or log($a)/log(10) |
$c = sprintf("%0.3f", ln($a)/ln(10) ); # or log($a)/log(10) |
Revision as of 19:25, 16 January 2010
Formatting Decimals: PG Code Snippet
We show how to format decimals for display in PG problems. Note that these are insertions, not a complete PG file. This code will have to be incorporated into the problem file on which you are working.
PG problem file | Explanation |
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DOCUMENT(); loadMacros( "PGstandard.pl", "MathObjects.pl" ); TEXT(beginproblem()); |
Initialization: Standard. |
# # both ln and log are natural log (base e) # $a = 6; # or $a = random(3,7,1); # # log base e # $b = sprintf("%0.3f", ln($a) ); # or log($a) $solution1 = Real("$b"); $f = Formula("ln(x)"); # or log(x) $solution2 = $f->eval(x=>$a); # # log base 10 is log10, logten, # ln(x)/ln(10), or log(x)/log(10) # $c = sprintf("%0.3f", ln($a)/ln(10) ); # or log($a)/log(10) $solution3 = Real("$c"); $g = Formula("ln(x)/ln(10)"); # or log(x)/log(10) $solution4 = $g->eval(x=>$a); |
Setup:
Use perl's We used the logarithm change of base formula log_{10}(a) = log(a) / log(10) = ln(a) / ln(10) to get a logarithm base 10.
Note: If we load |
Context()->texStrings; BEGIN_TEXT Notice the formatting and rounding differences between \( $solution1 \) and \( $solution2 \). $BR $BR Try entering \( \ln($a), \log($a), \ln($a)/\ln(10), \log($a)/\log(10), \mathrm{logten}($a), \mathrm{log10}($a) \). $BR $BR \( \ln($a) = \) \{ ans_rule(20) \} $BR \( \ln($a) = \) \{ ans_rule(20) \} $BR \( \log_{10}($a) = \) \{ ans_rule(20) \} $BR \( \log_{10}($a) = \) \{ ans_rule(20) \} END_TEXT Context()->normalStrings; |
Main Text: Notice the difference in decimal formatting when "Show Correct Answers" is checked and you click "Submit Answers". |
ANS( $solution1->cmp() ); ANS( $solution2->cmp() ); ANS( $solution3->cmp() ); ANS( $solution4->cmp() ); ENDDOCUMENT(); |
Answer Evaluation: Standard. |