The differential equation is given as follows:
y′′ + p(x) y′ + q(x) y = F(x)
with the initial values
y(x_{0}) = y_{0} and y′(x_{0}) = y′_{0}
The solution of the differential equation 2.order is calculated numerically. The method can be selected. Three Runge-Kutta methods are available: Heun, Euler and Runge-Kutta 4.Order. The initial values for y_{0} and y′_{0} can be varied by pulling the dots in the charts. The value for x_{0} can be set in numeric input field right. In the text boxes for the functions p, q and F up to three parameters a, b and c can be used which can be varied by means of the slider in the upper graph. In state-space diagram the solutions y_{1} and y_{2} of the corresponding first order differential equation system are applied. The diagram shows y_{2} over y_{1}. The number of grid vectors in state-space diagram can be set in the numeric field for the grid points. In the state-space diagram is plotted y_{2} on the vertical axis and y_{1} about the horizontal axis.
Grap the start point to move the initial values. The grid vectors show the initial direction if the ODE starts at this points.
p(x) =
q(x) =
F(x) =
With a substitution the differential equation of second order can be transformed to a differential system of first order.
Substitution:
y_{1} = y
y_{2} = y′
So the resulting ODE system of 1.order is:
y_{1}′ = y_{2}
y_{2}′ = F(x) - p(x) y_{2} - q(x) y_{1}
Constants
Name | Description |
---|---|
LN2 | Natural logarithm of 2 |
LN10 | Natural logarithm of 10 |
LOG2E | Base 2 logarithm of EULER |
LOG10E | Base 10 logarithm of EULER |
PI | Ratio of the circumference of a circle to its diameter |
SQRT1_2 | Square root of 1/2 |
SQRT2 | Square root of 2 |
Trigonometric Functions
Function | Description |
---|---|
sin(x) | sine of x |
cos(x) | Cosine of x |
tan(x) | Tangent of x |
asin(x) | arcsine |
acos(x) | arccosine of x |
atan(x) | arctangent of x |
atan2(y, x) | Returns the arctangent of the quotient of its arguments. |
cosh(x) | Hyperbolic cosine of x |
sinh(x) | Hyperbolic sine of x |
Logarithm and Exponential
Function | Description |
---|---|
pow(b, e) | e to the b |
sqrt(x) | Square root of x |
exp(x) | EULER to the x |
log(x), ln(x) | Natural logarithm |
log(x, b) | Logarithm to base b |
log2(x), lb(x) | Logarithm to base 2 |
log10(x), ld(x) | Logarithm to base 10 |
More functions
Function | Description |
---|---|
ceil(x) | Get smallest integer n with n > x. |
abs(x) | Absolute value of x |
max(a, b, c, ...) | Maximum value of all given values. |
min(a, b, c, ...) | Minimum value of all given values. |
random(max = 1) | Generate a random number between 0 and max. |
round(v) | Returns the value of a number rounded to the nearest integer. |
floor(x) | Returns the biggest integer n with n < x. |
factorial(n) | Calculates n! |
trunc(v, p = 0) | Truncate v after the p-th decimal. |
V(s) | Returns the value of the given element, e.g. sliders and angles. |
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Calculator:
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y'+ay=b y'=fy+gy^n y'+2xy=xe^(-x^2) y'+xy=x y'+y=x y'=y^2 y'+y^2=1 y'=(Ay-a)(By-b)