Substitute symbol for value

subs(sym, nms, vls)

Arguments

sym: Expression
nms: Names of symbols (see Details)
vls: Values that nms is substituted with (see Details)

Details

Two different ways to call this function is supported:

Supplying nms as a named list and omitting vls. If two components have the same name, the behaviour is undefined.
Supplying both nms and vls See Examples.

Examples

if (has_sympy()) {
   x <- symbol('x')
   e <- 2*x^2
   e
   subs(e, "x", "2")
   subs(e, x, 2)
   subs(e, list(x = 2))
   
   A <- matrix_sym(2, 2, "a")
   B <- matrix_sym(2, 2, "b")
   e <- A %*% A
   subs(e, A, B)
}
#> c: ⎡    2                               ⎤
#>    ⎢ b₁₁  + b₁₂⋅b₂₁    b₁₁⋅b₁₂ + b₁₂⋅b₂₂⎥
#>    ⎢                                    ⎥
#>    ⎢                                 2  ⎥
#>    ⎣b₁₁⋅b₂₁ + b₂₁⋅b₂₂   b₁₂⋅b₂₁ + b₂₂   ⎦