# Sqrt Sqrt[z]

or gives the square root of z.

# Details • Mathematical function, suitable for both symbolic and numerical manipulation.
• can be entered using or (@z).
• Sqrt[z] is converted to .
• Sqrt[z^2] is not automatically converted to z.
• Sqrt[a b] is not automatically converted to Sqrt[a]Sqrt[b].
• These conversions can be done using PowerExpand, but will typically be correct only for positive real arguments.
• For certain special arguments, Sqrt automatically evaluates to exact values.
• Sqrt can be evaluated to arbitrary numerical precision.
• Sqrt automatically threads over lists.
• In StandardForm, Sqrt[z] is printed as .
• z can also be used for input. The character is entered as sqrt or \[Sqrt].

# Examples

open allclose all

## Basic Examples(6)

Evaluate numerically:

Enter using :

Negative numbers have imaginary square roots:

Plot over a subset of the reals:

Plot over a subset of the complexes: is not necessarily equal to :

It can be simplified to if one assumes :

## Scope(38)

### Numerical Evaluation(6)

Evaluate numerically:

Evaluate to high precision:

The precision of the output tracks the precision of the input:

Complex number inputs:

Evaluate efficiently at high precision:

Sqrt can deal with realvalued intervals:

Sqrt threads elementwise over lists and matrices:

### Specific Values(4)

Values of Sqrt at fixed points:

Values at zero:

Values at infinity:

Find a value of for which using Solve:

Substitute in the result:

Visualize the result:

### Visualization(4)

Plot the real and imaginary parts of the Sqrt function:

Compare the real and imaginary parts of and (Surd[x,2]):

Plot the real part of :

Plot the imaginary part of :

Polar plot with :

### Function Properties(10)

The real domain of Sqrt:

It is defined for all complex values:

Sqrt achieves all non-negative values on the reals:

The range for complex values is the right half-plane, excluding the negative imaginary axis:

Find limits at branch cuts:

Enter a character as sqrt or \[Sqrt], followed by a number: is not an analytic function:

Nor is it meromorphic: is neither non-decreasing nor non-increasing:

However, it is increasing where it is real valued: is injective:

Not surjective: is non-negative on its domain of definition: has a branch cut singularity for :

However, it is continuous at the origin: is neither convex nor concave:

However, it is concave where it is real valued:

### Differentiation(3)

The first derivative with respect to z:

Higher derivatives with respect to z:

Plot the higher derivatives with respect to z:

Formula for the  derivative with respect to z:

### Integration(3)

Compute the indefinite integral using Integrate:

Verify the anti-derivative:

Definite integral:

More integrals:

### Series Expansions(4)

Find the Taylor expansion using Series:

Plots of the first three approximations around :

The general term in the series expansion using SeriesCoefficient:

The first-order Fourier series:

The Taylor expansion at a generic point:

### Function Identities and Simplifications(4)

Primary definition:

Connection with Exp and Log: is not automatically replaced by :

It can be simplified to if one assumes :

It can be simplified to if one assumes :

PowerExpand can be used to force cancellation without assumptions:

Expand assuming real variables x and y:

## Applications(4)

Generate periodic continued fractions:

Solve a differential equation with Sqrt:

Compute an elliptic integral from the Sqrt function:

## Properties & Relations(12)

Sqrt[x] and Surd[x,2] are the same for non-negative real values:

For negative reals, Sqrt gives an imaginary result, whereas the real-valued Surd reports an error: Reduce combinations of square roots:

Evaluate power series involving square roots:

Expand a complex square root assuming variables are real valued:

Factor polynomials with square roots in coefficients:

Simplify handles expressions involving square roots:

There are many subtle issues in handling square roots for arbitrary complex arguments:

PowerExpand expands forms involving square roots:

It generically assumes that all variables are positive:

Finite sums of integers and square roots of integers are algebraic numbers:

Take limits accounting for branch cuts:

Sqrt can be represented as a DifferentialRoot:

The generating function for Sqrt:

## Possible Issues(3)

Square root is discontinuous across its branch cut along the negative real axis:

Sqrt[x^2] cannot automatically be reduced to x:

With x assumed positive, the simplification can be done:

Use PowerExpand to do the formal reduction:

Along the branch cut, these are not the same:

## Neat Examples(2)

Approximation to GoldenRatio:

Riemann surface for square root: