Run yacas command returning string/character
yac_str(x)yacas command
yac_str("D(x) x^2 + 4*x")
#> [1] "2*x+4"
yac_str("Limit(x, 1) (x^2 - 1)/(x - 1)")
#> [1] "2"
yac_str("Sum(n, 1, Infinity, (1/2)^n)")
#> [1] "1"
yac_str("Fibonacci(10)")
#> [1] "55"
yac_str("Sum(n, 1, 10, Fibonacci(n))")
#> [1] "143"
yac_str("TeXForm(x^2 - 1)")
#> [1] "x ^{2} - 1"