MATLAB Function Reference
deval

Evaluate the solution of a differential equation problem

Syntax

• ```sxint = deval(sol,xint)
sxint = deval(xint,sol)
sxint = deval(sol,xint,idx)
sxint = deval(xint,sol,idx)
```

Description

```sxint = deval(sol,xint) and sxint = deval(xint,sol) ``` evaluate the solution of a differential equation problem. `sol` is a structure returned by one of these solvers:

• An initial value problem solver (`ode45`, `ode23`, `ode113`, `ode15s`, `ode23s`, `ode23t`, `ode23tb`),
• The delay differential equations solver (`dde23`),
• The boundary value problem solver (`bvp4c`).

`xint` is a point or a vector of points at which you want the solution. The elements of `xint` must be in the interval `[sol.x(1),sol.x(end)]`. For each `i`, `sxint(:,i)` is the solution at `xint(i)`.

```sxint = deval(sol,xint,idx) and sxint = deval(xint,sol,idx) ``` evaluate as above but return only the solution components with indices listed in `idx`.

Example

This example solves the system using `ode45`, and evaluates and plots the first component of the solution at 100 points in the interval `[0,20]`.

• ```sol = ode45(@vdp1,[0 20],[2 0]);
x = linspace(0,20,100);
y = deval(sol,x,1);
plot(x,y);

```

ODE solvers: `ode45`, `ode23`, `ode113`, `ode15s`, `ode23s`, `ode23t`, `ode23tb`
DDE solver: `dde23`
BVP solver: `bvp4c`