num_cmp
num_cmp
Description
Creates an answer evaluator which checks numerical answers.
Syntax
num_cmp(number, options)num_cmp([num1, num2], options)
Params
The first argument is the correct numerical answer, or one or more correct answers placed in square brackets. The options are specified in
key => value(see Options)
Options
Option key Option value Default mode 'std' -- (default) - allows any expression evaluating to a number
'frac' -- fractions are allowed
'arith' -- arithmetic expressions allowed
'strict' -- only numbers are allowed'std' tol an absolute tolerance for checking answers -- the default is to use relative tolerance reltol submit_ans-corr_ans| < .01 * reltol *corr_ans. .01 per cent format defines formatting for printing the correct answer using the perl and C conventions. '%0.5f'units specifies that the answer must include units and specifies the units used for the correct answer. strings specifies a list of words which are also allowed. (e.g. -- ['infinity','minus_infinity','undefined'] ). Note the required square brackets.
Returns
One (or more) answer evaluators
Examples
*
num_cmp( 5, mode => 'strict' )allows only 5 as an answer. No calculations are done.
*num_cmp( 5, mode => 'arith' )allows (3+7)/2 as an answer but not (2 +6)/2 + cos(0)
*num_cmp( 5, mode => 'frac' )allows 10/2 as an answer but not 3+5. This option is intended to allow numbers containing fractions, but it general will not do arithmetic operations.
*num_cmp( 5 ) or num_cmp(5, mode =>'std')allow cos(0) + e^0 +6/2 as an answer
*num_cmp(10, tol => 1)requires an answer between 9 and 11.(There is ambiguity at the endpoints.)
*num_cmp(10, reltol=>1)requires an answer between 9.9 and 10.1 -- i.e. within 1% of the correct answer. (reltol is defined in percent!)
*num_cmp( 3.1415926, format =>'%0.3f' )prints as 3.141
*num_cmp( 3.14159, format => '%0.4e' )prints as 3.1415
*num_cmp( 3.14159, format =>'%0.3g' )gives 4 figures in either fixed point or exponential notation depending on the size. In this case 3.14. For very small or large numbers the answer would be printed using exponential notation.
*num_cmp(5, units => 'cm')requires '5 cm' or '50 mm' or '.05 m' as an answer. The submitted answer must have a space before the unit and no spaces within the units.
*num_cmp(5, strings =>['undefined'])requires either a 5 or 'undefined' as an answer.
Notes
The options can be used in any combination that makes sense, and probably some that don't. One exception:
reltolandtolcannot be used together.
