warning: Solving was not successful. The iterative integration loop exited at time t = 0.000000 before the endpoint at tend = 0.001000 was reached

Hi,I'm trying to solve a big system of ODE here is my code with ODE45

k1 k2 k3...
    
F=@(t,n)([k1*n(2)*n(42)+k15*n(5)*n(9)+k16*n(5)*n(26)+k25*n(4)*n(26)...
.+k29*n(4)*n(9)+k33*n(4)*n(11)+k39*n(7)*n(26)+k40*n(7)*n(27)...
.+k43*n(7)*n(9)+k44*n(7)*n(12)+k48*n(9)*n(9)+k59*n(11)*n(42)...
.+k72*n(2)*n(24)+k104*n(3)*n(5)+k105*n(3)*n(8)+k106*n(3)*n(25)...
.+k117*n(18)*n(2)+k119*n(3)*n(43)+k122*n(11)*n(43)+k124*n(13)*n(43)...
.+k130*n(22)*n(43)-k4*n(1)*n(37)-k8*n(1)*n(15)-k9*n(1)*n(26)...
.-k10*n(1)*n(24)-k11*n(1)*n(20)-k12*n(1)*n(35)-k13*n(1)*n(22)...
.-k61*n(2)*n(1)-k64*n(1)*n(13)-k65*n(1)*n(4)-k66*n(1)*n(9)...
.-k67*n(1)*n(5)-k68*n(1)*n(1)-k69*n(1)*n(7)-k73*n(1)*n(27)...
.-k74*n(1)*n(11)-k75*n(1)*n(23)-k76*n(1)*n(21)-k77*n(1)*n(19)...
.-k118*n(1)*n(43)-k132*n(1)*n(42)-k136*n(1)*n(3)-k137*n(1)*n(12)...
.-k138*n(1)*n(14)-k139*n(1)*n(6)-2*k164*n(7)*n(1)*n(1)...
.+k164*n(7)*n(1)^(2)-k163*n(1)*n(15)*n(4)+k163*n(1)*n(15)*n(4)...
.-k165*n(1)*n(32)*n(4)+k165*n(1)*n(32)*n(4);%Chemin réactionnel C
-k1*n(2)*n(42)-k5*n(2)*n(15)-k6*n(2)*n(30)-k7*n(2)*n(36)...
.-k61*n(2)*n(1)-k62*n(2)*n(7)-k63*n(2)*n(4)-k72*n(2)*n(24)...
.-k117*n(18)*n(2)+k45*n(7)*n(11)+k73*n(1)*n(27)...
.+k74*n(1)*n(11)+k75*n(1)*n(23)+k76*n(1)*n(21)...
.+k77*n(1)*n(19)+k118*n(1)*n(43)+k122*n(11)*n(43);%chemin reactionnel C+
k32*n(4)*n(12)+k132*n(1)*n(42)-k14*n(3)*n(24)-k104*n(3)*n(5)...
.-k105*n(3)*n(8)-k106*n(3)*n(25)-k119*n(3)*n(43)...
.-k136*n(1)*n(3)-k140*n(3)*n(4)-k141*n(3)*n(15)-k142*n(3)*n(7); %Chemin réactionnel C-
k2*n(5)*n(42)+k8*n(1)*n(15)+k10*n(1)*n(24)+k13*n(1)*n(22)...
.+k14*n(3)*n(24)+k35*n(7)*n(15)+k36*n(7)*n(19)...
.+k37*n(7)*n(24)+k38*n(7)*n(32)+k52*n(15)*n(24)...
.+k53*n(15)*n(20)+k55*n(15)*n(22)+k56*n(15)*n(26)...
.+k78*n(5)*n(9)+k79*n(5)*n(22)+k80*n(5)*n(30)...
.+k81*n(5)*n(15)+k84*n(6)*n(15)+k85*n(6)*n(26)...
.+k104*n(3)*n(5)+2*k107*n(5)*n(6)+k108*n(5)*n(18)...
.+k109*n(6)*n(8)+k120*n(6)*n(43)+2*k126*n(15)*n(43)...
.+k128*n(19)*n(43)+k130*n(22)*n(43)+k131*n(24)*n(43)...
.+k162*n(42)*n(4)*n(15)-k19*n(4)*n(24)-k20*n(4)*n(32)...
.-k21*n(4)*n(30)-k22*n(4)*n(30)-k23*n(4)*n(20)...
.-k24*n(4)*n(36)-k25*n(4)*n(26)-k26*n(4)*n(26)...
.-k27*n(4)*n(13)-k28*n(4)*n(35)-k29*n(4)*n(9)...
.-k30*n(4)*n(21)-k31*n(4)*n(14)-k32*n(4)*n(12)...
.-k33*n(4)*n(11)-k63*n(2)*n(4)-k65*n(1)*n(4)...
.-2*k70*n(4)*n(4)-k82*n(4)*n(21)-k83*n(4)*n(23)...
.-k133*n(4)*n(42)-k140*n(3)*n(4)-k143*n(4)*n(6)...
.-k144*n(4)*n(12)-k161*n(42)*n(4)*n(15)...
.-k162*n(42)*n(4)*n(15)-k163*n(1)*n(15)*n(4)-k165*n(1)*n(32)*n(4);%Chemin réactionnel O
k5*n(2)*n(15)+k34*n(8)*n(15)+k82*n(4)*n(21)...
.+k83*n(4)*n(23)+k128*n(19)*n(43)-k19*n(4)*n(24)...
.-k20*n(4)*n(32)-k21*n(4)*n(30)-k22*n(4)*n(30)...
.-k23*n(4)*n(20)-k24*n(4)*n(36)-k25*n(4)*n(26)...
.-k26*n(4)*n(26)-k27*n(4)*n(13)-k28*n(4)*n(35)...
.-k29*n(4)*n(9)-k30*n(4)*n(21)-k31*n(4)*n(14)...
.-k32*n(4)*n(12)-k33*n(4)*n(11)-k63*n(2)*n(4)...
.-k65*n(1)*n(4)-2*k70*n(4)*n(4)-k82*n(4)*n(21)...
.-k83*n(4)*n(23)-k133*n(4)*n(42)-k140*n(3)*n(4)...
.-k143*n(4)*n(6)-k144*n(4)*n(12)-k161*n(42)*n(4)*n(15)...
.-k162*n(42)*n(4)*n(15)-k163*n(1)*n(15)*n(4)-k165*n(1)*n(32)*n(4);%Chemin réactionnel O+
k133*n(4)*n(42)+k161*n(42)*n(4)*n(15)-k84*n(6)*n(15)...
.-k85*n(6)*n(26)-k107*n(5)*n(6)-k109*n(6)*n(8)-k120*n(6)*n(43)...
.-k139*n(1)*n(6)-k143*n(4)*n(6)-k145*n(6)*n(24)...
.-k146*n(6)*n(22)-k147*n(6)*n(7);% %Chemin réactionnel O-
k3*n(8)*n(42)+k9*n(1)*n(26)+k11*n(1)*n(20)...
.+k18*n(5)*n(20)+k19*n(4)*n(24)+k23*n(4)*n(20)...
.+k26*n(4)*n(26)+k30*n(4)*n(21)+2*k60*n(21)*n(42)...
.+k86*n(8)*n(15)+k87*n(8)*n(9)+k88*n(8)*n(22)...
.+k89*n(8)*n(26)+k90*n(8)*n(24)+k105*n(3)*n(8)...
.+k109*n(6)*n(8)+k110*n(8)*n(18)+k111*n(8)*n(12)...
.+k112*n(8)*n(28)+k113*n(8)*n(14)+2*k129*n(20)*n(43)...
.+k131*n(24)*n(43)+2*k159*n(20)*n(42)-k35*n(7)*n(15)...
.-k36*n(7)*n(19)-k37*n(7)*n(24)-k38*n(7)*n(32)...
.-k39*n(7)*n(26)-k40*n(7)*n(27)-k41*n(7)*n(13)...
.-k42*n(7)*n(14)-k43*n(7)*n(9)-k44*n(7)*n(12)...
.-k45*n(7)*n(11)-k46*n(7)*n(35)-k62*n(2)*n(7)...
.-k69*n(1)*n(7)-k71*n(8)*n(7)-k91*n(7)*n(21)...
.-k142*n(3)*n(7)-k147*n(6)*n(7)-k164*n(7)*n(1)*n(1);%Chemin réactionnel N
k91*n(7)*n(21)-k3*n(8)*n(42)-k34*n(8)*n(15)...
.-k71*n(8)*n(7)-k86*n(8)*n(15)-k87*n(8)*n(9)...
.-k88*n(8)*n(22)-k89*n(8)*n(26)-k90*n(8)*n(24)...
.-k105*n(3)*n(8)-k109*n(6)*n(8)-k110*n(8)*n(18)...
.-k111*n(8)*n(12)-k112*n(8)*n(28)-k113*n(8)*n(14);%Chemin réactionnel N+
k9*n(1)*n(26)+k12*n(1)*n(35)+k13*n(1)*n(22)...
.+k27*n(4)*n(13)+k41*n(7)*n(13)+k68*n(1)*n(1)...
.+k74*n(1)*n(11)+k94*n(11)*n(24)+k111*n(8)*n(12)...
.+k115*n(12)*n(25)+k121*n(9)*n(43)+k123*n(12)*n(43)...
.+k124*n(13)*n(43)+k136*n(1)*n(3)+k153*n(10)*n(42)...
.+k154*n(10)^(2)+k155*n(10)*n(1)-k15*n(5)*n(9)...
.-k29*n(4)*n(9)-k43*n(7)*n(9)-k47*n(9)*n(15)...
.-2*k48*n(9)*n(9)-k49*n(9)*n(19)-k66*n(1)*n(9)...
.-k78*n(5)*n(9)-k87*n(8)*n(9)-k92*n(9)*n(23)...
.-k93*n(9)*n(27)-k121*n(9)*n(43)-k134*n(9)*n(42)...
.-k148*n(9)*n(12)-k150*n(9)*n(42);%Chemin réactionnel C2 
k150*n(9)*n(42)-k153*n(10)*n(42)-k154*n(10)^(2)-k155*n(10)*n(1);%C2(d)
k61*n(2)*n(1)+k78*n(5)*n(9)+k87*n(8)*n(9)...
.+k92*n(9)*n(23)+k93*n(9)*n(27)-k33*n(4)*n(11)...
.-k45*n(7)*n(11)-k50*n(11)*n(15)-k59*n(11)*n(42)...
.-k74*n(1)*n(11)-k94*n(11)*n(24)-k122*n(11)*n(43);%Chemin réactionnel C2+
-k32*n(4)*n(12)-k44*n(7)*n(12)-k111*n(8)*n(12)...
.-k115*n(12)*n(25)-k123*n(12)*n(43)-k137*n(1)*n(12)...
.-k144*n(4)*n(12)-k148*n(9)*n(12)-k149*n(12)*n(13)...
.+k31*n(4)*n(14)+k42*n(7)*n(14)+k134*n(9)*n(42);%Chemin réactionnel C2-
k48*n(9)*n(9)+k66*n(1)*n(9)+k113*n(8)*n(14)...
.+k114*n(14)*n(25)+k125*n(14)*n(43)...
.+k137*n(1)*n(12)-k27*n(4)*n(13)-k41*n(7)*n(13)...
.-k64*n(1)*n(13)-k124*n(13)*n(43)...
.-k135*n(13)*n(42)-k149*n(12)*n(13);%Chemin réactionnel C3 
k135*n(13)*n(42)-k31*n(4)*n(14)...
.-k42*n(7)*n(14)-k113*n(8)*n(14)...
.-k114*n(14)*n(25)-k125*n(14)*n(43)-k138*n(1)*n(14);%Chemin réactionnel C3-
k17*n(5)*n(32)+k19*n(4)*n(24)+k20*n(4)*n(32)...
.+k21*n(4)*n(30)+k57*n(24)*n(24)+k70*n(4)*n(4)...
.+k77*n(1)*n(19)+k97*n(19)*n(32)+k98*n(19)*n(24)...
.+k108*n(5)*n(18)+k110*n(8)*n(18)+k116*n(18)*n(25)...
.+k117*n(18)*n(2)+k127*n(18)*n(43)+k143*n(4)*n(6)...
.+2*k156*n(18)*n(15)+2*k157*n(18)*n(16)...
.+2*k158*n(18)*n(17)+k161*n(42)*n(4)*n(15)...
.-k5*n(2)*n(15)-k8*n(1)*n(15)-k34*n(8)*n(15)...
.-k35*n(7)*n(15)-k47*n(9)*n(15)-k50*n(11)*n(15)...
.-k51*n(15)*n(37)-k52*n(15)*n(24)-k53*n(15)*n(20)...
.-k54*n(15)*n(27)-k55*n(15)*n(22)-k56*n(15)*n(26)...
.-k81*n(5)*n(15)-k84*n(6)*n(15)-k86*n(8)*n(15)...
.-k95*n(15)*n(21)-k96*n(15)*n(23)-k126*n(15)*n(43)...
.-k141*n(3)*n(15)-k151*n(15)*n(42)-k152*n(15)*n(42)...
.-k156*n(18)*n(15)-k161*n(42)*n(4)*n(15)...
.-k162*n(42)*n(4)*n(15)-k163*n(1)*n(15)*n(4);%Chemin réactionnel O2 
k151*n(42)*n(15)-k157*n(16)*n(18);%Chemin réactionnel O2(a) 
k152*n(42)*n(15)-k158*n(17)*n(18);%Chemin réactionnel O2(b) 
k84*n(6)*n(15)+k162*n(42)*n(4)*n(15)...
.-k108*n(5)*n(18)-k110*n(8)*n(18)...
.-k116*n(18)*n(25)-k117*n(18)*n(2)-k127*n(18)*n(43)...
.-k156*n(18)*n(15)-k157*n(18)*n(16)-k158*n(18)*n(17);%Chemin réactionnel O2-
k81*n(5)*n(15)+k86*n(8)*n(15)+k95*n(15)*n(21)...
.+k96*n(15)*n(23)-k36*n(7)*n(19)-k49*n(9)*n(19)-k77*n(1)*n(19)...
.-k97*n(19)*n(32)-k98*n(19)*n(24)-k128*n(19)*n(43);%Chemin réactionnel O2+
k21*n(4)*n(30)+k37*n(7)*n(24)+k39*n(7)*n(26)...
.+k57*n(24)*n(24)+k76*n(1)*n(21)+k82*n(4)*n(21)...
.+k91*n(7)*n(21)+k95*n(15)*n(21)+k99*n(21)*n(26)...
.+k100*n(21)*n(22)-k11*n(1)*n(20)-k18*n(5)*n(20)...
.-k23*n(4)*n(20)-k53*n(15)*n(20)...
.-k129*n(20)*n(43)-k159*n(20)*n(42)-k160*n(20)*n(42);%Chemin réactionnel N2
k40*n(7)*n(27)+k71*n(8)*n(7)+k160*n(20)*n(42)...
.-k30*n(4)*n(21)-k60*n(21)*n(42)-k76*n(1)*n(21)...
.-k82*n(4)*n(21)-k91*n(7)*n(21)...
.-k95*n(15)*n(21)-k99*n(21)*n(26)-k100*n(21)*n(22);%Chemin réactionnel N2+
k4*n(1)*n(37)+k5*n(2)*n(15)+k8*n(1)*n(15)...
.+k24*n(4)*n(36)+k26*n(4)*n(26)+k27*n(4)*n(13)...
.+k28*n(4)*n(35)+k29*n(4)*n(9)+k31*n(4)*n(14)...
.+k32*n(4)*n(12)+2*k47*n(9)*n(15)+k49*n(9)*n(19)...
.+k50*n(11)*n(15)+k54*n(15)*n(27)+k58*n(24)*n(37)...
.+k65*n(1)*n(4)+k75*n(1)*n(23)+k83*n(4)*n(23)...
.+k92*n(9)*n(23)+k96*n(15)*n(23)+k102*n(24)*n(23)...
.+k139*n(1)*n(6)+k140*n(3)*n(4)-k13*n(1)*n(22)...
.-k55*n(15)*n(22)-k79*n(5)*n(22)-k88*n(8)*n(22)...
.-k100*n(21)*n(22)-k101*n(22)*n(27)...
.-k130*n(22)*n(43)-k146*n(6)*n(22);%Chemin réactionnel CO 
k7*n(2)*n(36)+k15*n(5)*n(9)+k33*n(4)*n(11)...
.+k49*n(9)*n(19)+k50*n(11)*n(15)+k63*n(2)*n(4)...
.+k67*n(1)*n(5)+k79*n(5)*n(22)+k88*n(8)*n(22)...
.+k100*n(21)*n(22)+k101*n(22)*n(27)-k75*n(1)*n(23)...
.-k83*n(4)*n(23)-k92*n(9)*n(23)...
.-k96*n(15)*n(23)-k102*n(24)*n(23);%Chemin réactionnel CO+ 
k20*n(4)*n(32)+k22*2*n(4)*n(30)+k23*n(4)*n(20)...
.+k24*n(4)*n(36)+k25*n(4)*n(26)+k34*n(8)*n(15)...
.+k35*n(7)*n(15)+k51*n(15)*n(37)+k106*n(3)*n(25)...
.+k114*n(14)*n(25)+k115*n(12)*n(25)+k116*n(18)*n(25)...
.+k147*n(6)*n(7)-k10*n(1)*n(24)-k14*n(3)*n(24)-k19*n(4)*n(24)...
.-k37*n(7)*n(24)-k52*n(15)*n(24)-k57*2*n(24)*n(24)...
.-k58*n(24)*n(37)-k72*n(2)*n(24)-k90*n(8)*n(24)...
.-k94*n(11)*n(24)-k98*n(19)*n(24)-k102*n(24)*n(23)...
.-k103*n(24)*n(27)-k131*n(24)*n(43)-k145*n(6)*n(24);%Chemin réactionnel NO 
k6*n(2)*n(30)+k16*n(5)*n(26)+k17*n(5)*n(32)...
.+k18*n(5)*n(20)+k30*n(4)*n(21)+k36*n(7)*n(19)...
.+k54*n(15)*n(27)+k72*n(2)*n(24)+k90*n(8)*n(24)...
.+k94*n(11)*n(24)+k98*n(19)*n(24)+k102*n(24)*n(23)...
.+k103*n(24)*n(27)-k106*n(3)*n(25)-k114*n(14)*n(25)...
.-k115*n(12)*n(25)-k116*n(18)*n(25);%Chemin réactionnel NO+ 
k4*n(1)*n(37)+k6*n(2)*n(30)+k7*n(2)*n(36)...
.+k10*n(1)*n(24)+k11*n(1)*n(20)+k12*n(1)*n(35)...
.+k28*n(4)*n(35)+k41*n(7)*n(13)+k42*n(7)*n(14)...
.+k43*n(7)*n(9)+k45*n(7)*n(11)+k46*2*n(7)*n(35)...
.+k69*n(1)*n(7)+k73*n(1)*n(27)+k93*n(9)*n(27)...
.+k101*n(22)*n(27)+k103*n(24)*n(27)...
.+k112*n(8)*n(28)+k142*n(3)*n(7)...
.+k164*n(7)*n(1)*n(1)-k9*n(1)*n(26)-k16*n(5)*n(26)...
.-k25*n(4)*n(26)-k26*n(4)*n(26)-k39*n(7)*n(26)...
.-k56*n(15)*n(26)-k85*n(6)*n(26)...
.-k89*n(8)*n(26)-k99*n(21)*n(26);%Chemin réactionnel CN 
k62*n(2)*n(7)+k89*n(8)*n(26)+k99*n(21)*n(26)...
.-k40*n(7)*n(27)-k54*n(15)*n(27)...
.-k73*n(1)*n(27)-k93*n(9)*n(27)...
.-k101*n(22)*n(27)-k103*n(24)*n(27);%Chemin réactionnel CN+
k14*n(3)*n(24)+k44*n(7)*n(12)+k85*n(6)*n(26)-k112*n(8)*n(28);%CN-
k163*n(1)*n(15)*n(4);%Chemin réactionnel O3 
k38*n(7)*n(32)+k53*n(15)*n(20)+k58*n(24)*n(37)...
.-k6*n(2)*n(30)-k21*n(4)*n(30)...
.-k22*n(4)*n(30)-k80*n(5)*n(30);%Chemin réactionnel N2O 
k80*n(5)*n(30);%Chemin réactionnel N2O+
k52*n(15)*n(24)+k145*n(6)*n(24)-k17*n(5)*n(32)...
.-k20*n(4)*n(32)-k38*n(7)*n(32)...
.-k97*n(19)*n(32)-k165*n(1)*n(32)*n(4);%Chemin réactionnel NO2 
k97*n(19)*n(32);%Chemin réactionnel NO2+
k51*n(15)*n(37)+k55*n(15)*n(22)...
.+k141*n(3)*n(15)+k146*n(6)*n(22);%Chemin réactionnel CO2 
-k12*n(1)*n(35)-k28*n(4)*n(35)-k46*n(7)*n(35);%Chemin réactionnel C2N 
-k7*n(2)*n(36)-k24*n(4)*n(36);%Chemin réactionnel CNO 
-k4*n(1)*n(37)-k51*n(15)*n(37)...
.-k58*n(24)*n(37)+k56*n(15)*n(26);%Chemin réactionnel OCN 
k165*n(1)*n(32)*n(4);%Chemin réactionnel NO3 
k144*n(4)*n(12);%Chemin réactionnel C2O 
k64*n(1)*n(13)+k138*n(1)*n(14)+k148*n(9)*n(12);%Chemin réactionnel C4 
k149*n(12)*n(13);%Chemin réactionnel C5 
k118*n(1)*n(43)+k119*n(3)*n(43)+k120*n(6)*n(43)...
.+k121*n(12)*n(43)+k123*n(12)*n(43)+k125*n(14)*n(43)...
.+k127*n(18)*n(43)+k136*n(1)*n(3)+k137*n(1)*n(12)...
.+k138*n(1)*n(14)+k139*n(1)*n(6)+k140*n(3)*n(4)...
.+k141*n(3)*n(15)+k142*n(3)*n(7)+k143*n(4)*n(6)...
.+k144*n(4)*n(12)+k145*n(6)*n(24)+k146*n(6)*n(22)...
.+k147*n(6)*n(7)+k148*n(9)*n(12)+k149*n(12)*n(13)...
.+k150*n(9)*n(42)+k151*n(15)*n(42)+k152*n(15)*n(42)...
.+k153*n(10)*n(42)+k156*n(18)*n(15)+k157*n(18)*n(16)...
.+k158*n(18)*n(17)+k159*n(20)*n(42)...
.+2*k160*n(20)*n(42)-k1*n(2)*n(42)-k2*n(5)*n(42)...
.-k3*n(8)*n(42)-k59*n(11)*n(42)-k60*n(21)*n(42)...
.-k132*n(1)*n(42)-k133*n(4)*n(42)-k134*n(9)*n(42)...
.-k135*n(13)*n(42)-k150*n(9)*n(42)-k151*n(15)*n(42)...
.-k152*n(15)*n(42)-k153*n(10)*n(42)-k159*n(20)*n(42)...
.-k160*n(20)*n(42)-k161*n(42)*n(4)*n(15)...
.-k162*n(42)*n(4)*n(15);%Chemin réactionnel e-
-k118*n(1)*n(43)-k119*n(3)*n(43)-k120*n(6)*n(43)...
.-k121*n(9)*n(43)-k122*n(11)*n(43)-k123*n(12)*n(43)...
.-k124*n(13)*n(43)-k125*n(14)*n(43)-k126*n(15)*n(43)...
.-k127*n(18)*n(43)-k128*n(19)*n(43)-k129*n(20)*n(43)...
.-k130*n(22)*n(43)-k131*n(24)*n(43)+k1*n(2)*n(42)...
.+k2*n(5)*n(42)+k3*n(8)*n(42)+k61*n(2)*n(1)...
.+k62*n(2)*n(7)+k63*n(2)*n(4)+k64*n(1)*n(13)...
.+k65*n(1)*n(4)+k66*n(1)*n(9)+k67*n(1)*n(5)...
.+k68*n(1)*n(1)+k69*n(1)*n(7)+k70*n(4)*n(4)...
.+k71*n(8)*n(7)+k132*n(1)*n(42)+k133*n(4)*n(42)...
.+k134*n(9)*n(42)+k135*n(13)*n(42)])
OPTs = OPTs = odeset('reltol', 1e-3, 'abstol', 1e-5)
tic,[Time, SOL]=ode45(F,[0 1e-3],IC, OPTs); 
toc                                                  
plot(Time,SOL) 

I got these errors

warning:  Solving was not successful.  The iterative integration loop exited
at time t = 0.000000 before the endpoint at tend = 0.001000 was reached.  Thi
s may happen if the stepsize becomes too small.  Try to reduce the value of '
InitialStep' and/or 'MaxStep' with the command 'odeset'.
warning: called from
    integrate_adaptive at line 318 column 7
    ode45 at line 241 column 12
    imene14echkabilov at line 246 column 16

Answer 1

[Jan]

The first guess in chemical systems is usually: The problem is stiff. Then you need a solver for stiff problems as ODE15S instead of the non-stiff ODE45.

By the way, the code does not run, because there are no ".+" and ".-" operators in Matlab.

The coe would be much easier to debug, if you do not squeeze a huge equation in a function handle, but if you write it to a function. I assume it the the result of some matrix equations. Then the matrix notation would be easier the debug and it even would run faster, most likely.

[Imene Yed]

thanks for the answer sir.Could you suggest to me another code please.

[Jan]

No, I can't, sorry. I do not have the faintest idea about what you are trying to calculate. Where does this huge equation come from? Who has inserted the ".+" and ".-" operators and what do they mean?

[Imene Yed]

when my ODE for exemple for n(1) was too long in the function hundle ,I wrote ...

then I came back to the next line ,the program didn't run ,so I added points and it worked.

[Jan]

The posted code does work?!

[Imene Yed]

yes it's working and I even get a graph ,the only problem is the warning that it appears solving was not succesfully......

[Steven Lord]

I second Jan's suggestion to create this as a function (either in a separate file or as a local function in the file where you call the ODE solver.) You can write this as an anonymous function but writing as a function will let you define variables with descriptive names that make the equations look closer to the actual chemical equations, extract subexpressions that are used repeatedly and so only evaluate them (and check that they are correct!) once, and more easily debug problems with the code. Think something like:

function dydt = myequations(t, y)
% Concentrations
O2conc = y(1);
CO2conv = y(2);
Nconv = y(3);
% now work with the oxygen, carbon dioxide, and nitrogen concentrations
% using the obviously named variables
end

Sure, you'll spend a couple extra seconds typing. [Tab completion may help mitigate that.] But if you choose your variable names well, you may not need to explain your code to anyone because it will be self documenting and that will save you time.

[Imene Yed]

thank you sir!