replace_powers does string manipulation

This function takes a string argument with human readable math (e.g. R code), and replaces the power operator z^n with C-compatible function calls: pow(x,n), it counts parentheses to determine the base and exponent automatically.

Usage

replace_powers(v)

Arguments

v

a character vector

Value

a string where all occurrences of ^ have been replaced by function calls like pow()

Details

This functions assumes that gsl functions can be used, the GNU Scientific Library includes powers of small integers. These functions may be faster than always calling pow from math.h.

This is necessary because in C the ^ operator means something else (exclusive bitwise xor for integers). No attempt will be made to cast the numbers to float or double.

Examples

print(replace_powers(c("2^3.1","10^-6","x^2","(1+(1+x))^(n-0.5)")))
#> [1] "pow(2, 3.1)"         "pow(10, -6)"         "gsl_pow_2(x)"       
#> [4] "pow(1+(1+x), n-0.5)"