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A list of functions that have been written that are available in the Safe space scripting environment inside a problem. The eventual - goal is to provide all of the functions available in CAPA + goal is to provide all of the functions available in CAPA. Detailed + descriptions of each function and comparison with CAPA is given in + CAPA to LON-CAPA Functions.

+ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
CAPA Functions + LON-CAPA + Descriptions + Differences (if any) +
sin(x), cos(x), tan(x)&sin($x), &cos($x), &tan($x)Trigonometric functions where x is in radians. $x + can be a pure number, i.e., you can call &sin(3.1415) 
sin(x), cos(x), tan(x)&sin($x), &cos($x), &tan($x)Trigonometric functions where x is in radians. $x + can be a pure number, i.e., you can call &sin(3.1415) 
asin(x), acos(x), atan(x), atan2(y,x)&asin($x), &acos($x), &atan($x), &atan2($y,$x)Inverse trigonometric functions. Return value is + in radians. For asin and acos the value of x must be between -1 and 1. + The atan2 returns a value between -pi and pi the sign of which is determined + by y. $x and $y can be pure numbers 
log(x), log10(x)&log($x), &log10($x)Natural and base-10 logarithm. $x can be a pure number 
exp(x), pow(x,y), sqrt(x)&exp($x), &pow($x,$y), &sqrt($x)Exponential, power and square root, i.e.,ex, xy and /x. $x and $y can be pure numbers 
abs(x), sgn(x)&abs($x), &sgn($x)Abs takes the absolute value of x while sgn(x) returns + 1, 0 or -1 depending on the value of x. For x>0, sgn(x) = 1, for x=0, sgn(x) + = 0 and for x<0, sgn(x) = -1. $x can be a pure number 
erf(x), erfc(x)&erf($x), &erfc($x)Error function.  erf = 2/sqrt(pi) integral (0,x) et-sq and erfx(x) = 1.0 - erf(x).  $x can be a pure number 
ceil(x), floor(x)&ceil($x), &floor($x)Ceil function returns an integer rounded up whereas + floor function returns and integer rounded down. If x is an integer than + it returns the value of the integer. $x can be a pure number 
min(...), max(...)&min(...), &max(...)Returns the minimum/ maximum value of a list of + arguments if the arguments are numbers. If the arguments are strings then + it returns a string sorted according to the ASCII codes 
factorial(n)&factorial($n)Argument (n) must be an integer else it will round + down. The largest value for n is 170. $n can be a pure number 
N%M$N%$MN and M are integers and returns the remainder (in + integer) of N/M. $N and $M can be pure numbers 
sinh(x), cosh(x), tanh(x)&sinh($x), &cosh($x), &tanh($x)Hyperbolic functions. $x can be a pure number 
asinh(x), acosh(x), atanh(x)&asinh($x), &acosh($x), &atanh($x)Inverse hyperbolic functions. $x can be a pure number 
roundto(x,n)&roundto($x,$n)Rounds a real number to n decimal points. $x and + $n can be pure numbers 
web("a","b","c") or web(a,b,c)&web("a","b","c") or &web($a,$b,$c)Returns either a, b or c depending on the output + medium. a is for plain ASCII, b for tex output and c for html output 
html("a") or html(a)&html("a") or &html($a)Output only if the output mode chosen is in html + format 
jn(m,x)&j0($x), &j1($x), &jn($m,$x), &jv($y,$x)Bessel functions of the first kind with orders 0, + 1 and m respectively. For jn(m,x), m must be an integer whereas for jv(y,x), + y is real. $x can be a pure number. $m must be an integer and can be a + pure integer number. $y can be a pure real numberIn CAPA, j0, j1 and jn are contained in one function, + jn(m,x) where m takes the value of 0, 1 or 2. jv(y,x) was not implemented
yn(m,x)&y0($x), &y1($x), &yn($m,$x), &yv($y,$x)Bessel functions of the second kind with orders + 0, 1 and m respectively. For yn(m,x), m must be an integer whereas for + yv(y,x), y is real. $x can be a pure number. $m must be an integer and + can be a pure integer number. $y can be a pure real numberIn CAPA, y0, y1 and yn are contained in one function, + yn(m,x) where m takes the value of 0, 1 or 2. yv(y,x) was not implemented
random(l,u,d)&random($l,$u,$d)Returns a uniformly distributed random number between + the lower bound, l and upper bound, u in steps of d. $l, $u and $d can + be pure numbersIn CAPA, all the 3 arguments must be of the same + type. However, now you can mix the type
choose(i,...)&choose($i,...)Choose the ith item from the argument list. i must + be an integer greater than 0 and the value of i should not exceed the number + of items. $i can be a pure integer 
tex(a,b), tex("a","b")&tex($a,$b), &tex("a","b")Returns a if the output mode is in tex otherwise + returns b 
var_in_tex(a)&var_in_tex($a)Equivalent to tex("a","") 
to_string(x), to_string(x,y)&to_string($x), &to_string($x,$y)If x is an integer, returns a string. If x is real + than the output is a string with format given by y. For example, if x = + 12.3456, &to_string(x,".3F") = 12.345 and &to_string(x,".3E") = + 1.234E+01. 
capa_id(), class(), section(), set(), problem()&class(), &section()Returns null string, class descriptive name, section + number, set number and null string.capa_id(), set() and problem() are no longer used. + Currently, they return a null value.
name(), student_number()&name(), &student_number()Return the full name in the following format: lastname, + firstname initial. Student_number returns the student 9-alphanumeric string. + If undefined, the functions return null. 
open_date(), due_date(), answer_date()&open_date(), &due_date(), &answer_date()Problem open date, due date and answer date. The + time is also included in 24-hr format.Output format for time is changed slightly. If pass + noon, it displays ..pm else it displays ..am. So 23:59 is displayed as + 11:59 pm.
get_seed(), set_seed()Not implementedGet and set the random seed. 
sub_string(a,b,c)&sub_string($a,$b,$c)
perl  substr function. + However, note the differences
Retrieve a portion of string a starting from b and + length c. For example,  $a = "Welcome to LON-CAPA"; + $result=&sub_string($a,4,4); then $result is "come"Perl intrinsic function, substr(string,b,c) starts + counting from 0 (as opposed to 1). In the example to the left, substr($a,4,4) + returns "ome ".
array[xx]@arrayname
Array is intrinsic in perl. + To access a specific element use $arrayname[$n] where $n + is the $n+1 element since the array count starts from 0
"xx" can be a variable or a calculation.In LON-CAPA, an array is defined by @arrayname. + It is not necessary to specify the dimension of the array. 
array_moments(B,A)@B=&array_moments(@A)Evaluates the moments of an array A and place the + result in array B[i] where i = 0 to 4. The contents of B are as follows: + B[0] = number of elements, B[1] = mean, B[2] = variance, B[3] = skewness + and B[4] = kurtosis. 
array_max(Name), array_min(Name)&min(@Name), &max(@Name)In LON-CAPA to find the maximum value of an array, use + &max(@arrayname)  and to find the minimum value of an array, use + &min(@arrayname)Combined with the min and max functions defined + earlier.
init_array(Name)undef @nameTo destroy the contents of an array, useUse perl intrinsic undef function.
random_norma(...), random_beta(...), random_gamma(...), + random_exponential(...), random_poisson(...), random_chi(...), random_noncentral(...)Not yet implemented.  
+ +

<script> Variables