Difference between revisions of "NSolve Command"
From GeoGebra Manual
m |
(* NSolve won't work for functions that are asymptotic to the x-axis. They can often be reformulated though) |
||
Line 17: | Line 17: | ||
;NSolve[ <List of Equations>, <List of Variables> ] | ;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. | :Attempts (numerically) to find a solution of the set of equations for the given set of unknown variables. | ||
− | :{{example|1=<div><code><nowiki>NSolve[{ | + | :{{example|1=<div><code><nowiki>NSolve[{pi / x = cos(x - 2y), 2 y - pi = sin(x)}, {x = 3, y = 1.5}]</nowiki></code> yields ''{x = 3.141592651686591, y = 1.570796327746508}''.</div>}} |
{{note| 1=<div> | {{note| 1=<div> | ||
* 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) | * 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 [[Options Menu#Runding|global rounding]]. | * The number of decimals depends on the choosen in [[Options Menu#Runding|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]]. | * See also [[Solve Command]] and [[NSolutions Command]]. | ||
</div>}} | </div>}} |
Revision as of 23:18, 13 June 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 {0.74}NSolve[a^4 + 34a^3 = 34, a = 3]
yields the list {-34, 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.