sqrt

Builtin index · Core maths

result = sqrt(x)

Input: x · Output: result

What it is

Elementwise square root. x is a scalar, Vec, or Mat/Signal; a negative element gives NaN (there is no automatic promotion to a complex result).

Overloads

One call shape — this function is not overloaded.

Code	Input	Output	Description
`result = sqrt(x)`	`x` scalar, Vec, Mat, or Signalnot documented yet	`result` —	Returns the same shape as `x`.

Examples

From the documentation, and run by the build -- the output and the figure below are what the engine actually produced. Simplest first.

unsafe as n_failed
    y = sqrt(-1)              # NaN, not an error -- just continues

    z = [1,2] + [1,2,3]       # a real error -- logged, counted, continues anyway

    print("still runs")
end
print("failures = {n_failed}")

from tour

pi_val = 3.14159265
print("pi = {pi_val:.2f}")
print("pi rounded = {pi_val:.0f}")
print("expr = {2+3*4}")
print("nested = {sqrt(16) + 1}")
v = [1,2,3]
print("vec sum = {sum(v):.1f}")

output

pi = 3.14
pi rounded = 3
expr = 14
nested = 5
vec sum = 6.0

from tour

tic()
for i in 1 to 1000000
    x = sqrt(i)
end
elapsed_s = toc()
print("took {elapsed_s:.4f}s")

output

took 0.0079s

from repl-diagnostics

A = randn(60, 200, seed = 7) / sqrt(60)
print("coherence {coherence(A):.3f}, provable sparsity {cs_guarantee(A)}")

output

coherence 0.558, provable sparsity 1

from compressed-sensing