# Difference between revisions of "NSolve Command"

From GeoGebra Manual

(* NSolve won't work for functions that are asymptotic to the x-axis. They can often be reformulated though) |
|||

Line 12: | Line 12: | ||

:Finds numerically the list of solutions to the given equation for the given unknown variable with its starting value. | :Finds numerically the list of solutions to the given equation for the given unknown variable with its starting value. | ||

:{{examples|1=<div> | :{{examples|1=<div> | ||

− | :*<code><nowiki>NSolve[cos(x) = x, x = 0]</nowiki></code> yields ''{0.74}'' | + | :*<code><nowiki>NSolve[cos(x) = x, x = 0]</nowiki></code> yields ''{x = 0.74}'' |

− | :*<code><nowiki>NSolve[a^4 + 34a^3 = 34, a = 3]</nowiki></code> yields | + | :*<code><nowiki>NSolve[a^4 + 34a^3 = 34, a = 3]</nowiki></code> yields ''{a = 0.99}''.</div>}} |

;NSolve[ <List of Equations>, <List of Variables> ] | ;NSolve[ <List of Equations>, <List of Variables> ] |

## Revision as of 11:33, 30 July 2015

- NSolve[ <Equation> ]
- Attempts (numerically) to find a solution for the equation for the main variable. For non-polynomials you should always specify a starting value (see below).
**Example:**`NSolve[x^6 - 2x + 1 = 0]`

yields*{x = 0.51, x = 1}*.

- NSolve[ <Equation>, <Variable> ]
- Attempts (numerically) to find a solution of the equation for the given unknown variable. For non-polynomials you should always specify a starting value (see below).
**Example:**`NSolve[a^4 + 34a^3 = 34, a]`

yields*{a = -34.00086498588374, a = 0.9904738885574178}*.

- NSolve[ <Equation>, <Variable = starting value> ]
- Finds numerically the list of solutions to the given equation for the given unknown variable with its starting value.
**Examples:**`NSolve[cos(x) = x, x = 0]`

yields*{x = 0.74}*`NSolve[a^4 + 34a^3 = 34, a = 3]`

yields*{a = 0.99}*.

- NSolve[ <List of Equations>, <List of Variables> ]
- Attempts (numerically) to find a solution of the set of equations for the given set of unknown variables.
**Example:**`NSolve[{pi / x = cos(x - 2y), 2 y - pi = sin(x)}, {x = 3, y = 1.5}]`

yields*{x = 3.141592651686591, y = 1.570796327746508}*.

**Note:**

- If you don't give a starting point like
*a=3*or*{x = 3, y = 1.5}*the numerical algorithm may find it hard to find a solution (and giving a starting point doesn't guarantee that a solution will be found) - The number of decimals depends on the choosen in global rounding.
- NSolve won't work for functions that are asymptotic to the x-axis. They can often be reformulated though
- See also Solve Command and NSolutions Command.