function derBH_Approx extends Modelica.Icons.Function; input Integer N "Count of exponential summands"; input SI.MagneticFieldStrength Hk[N] "Field strength coefficients"; input SI.MagneticFluxDensity Bk[N] "Flux density coefficients"; input SI.MagneticFieldStrength H "Field strength in ferromagnetic flux tube element"; input Real der_H(unit = "A/(m.s)") "Derivative of field strength in ferromagnetic flux tube element"; output Real der_B(unit = "T/s") "Derivative of flux density in ferromagnetic flux tube element"; end derBH_Approx;