Dear Sirs, My name is Susanna Filippi. I?m using your rkf45 algorithm for maxima to solve a differential equation of second order (here enclosed the file *.mc): de1: 'diff(Tv,z,2)=-'diff(Tv,z)*M_Al*C_Al(500)/(k_Al*%pi*Dv^2/4)- 4*h_v(340)*(Tv-340)/(k_Al*Dv); sol: rkf45([DTv,-4*85793*(Tv-Tin_acqua)/(k_Al*Dv)-DTv*4*M_Al*C_Al(Tv)/(k_Al*%pi*Dv^2)],[Tv,DTv],[Tin_Al,0],[z,0,1],absolute_tolerance=1/10^2,max_iterations=20000); When substituting to 85793 , h_v(340) that is 85793, the solver doesn?t work anymore. sol: rkf45([DTv,- 4*h_v(340)*(Tv-Tin_acqua)/(k_Al*Dv)-DTv*4*M_Al*C_Al(Tv)/(k_Al*%pi*Dv^2)],[Tv,DTv],[Tin_Al,0],[z,0,1],absolute_tolerance=1/10^2,max_iterations=20000);*/ /*it doesn't work: the substitution is just h_v(340); that is 85793 */ The error message is? Error: initial should be a list of numbers, but found [Tv, DTv] instead.#0: rkf45(odes=[DTv,-380855.9683943816*(Tv-308.15)/%pi^(4/5)-141036.5799018978*DTv/%pi],funcs=[Tv,DTv],initial=[633.15,0],interval=[z,0,1],options=[absolute_tolerance = 1/100,max_iterations = 20000])(rkf45.mac line 112)? Could you help me to solve the matter?
Thank you for your kind support and best regards. In the meanwhile I wish you a Happy New Year!!
Best regards.
Susanna Filippi
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