applying conditions in odesolver

equation of motion of projectile with drag is dvx/dt = -k*v*vx ; dvy/dt = -k*v*vy - g where k = drag coefficient and g = gravitational acceleration i solved this equation with ode solver (ode45) by giving a constant value of k and g. but in real the value of k and g vary with altitude i have the matrix for 'k' for different height interval .and the formula for variation of g with altitude. how to apply this conditional input to odesolver(ode45). so that odesolver(ode45) take different value of k and g at respective height range during steps .

please reply thanks pawan

Answer 1

[Jan]

Simply insert the formula for g in the ODE equation. For k I'd suggest an interpolation, if the values are read from a table: ODE45 expectes a smooth ODE function, but a naive lookup-table leads to discontinuities.