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Student Support Forum: 'How to calculate the partial derivative?' topicStudent Support Forum > General > "How to calculate the partial derivative?"

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Author Comment/Response
yehuda
11/25/12 08:38am

Try this one
It is base on leaving L1 and L2 as symbols, but defined as non constants, so derivatives according to x will not return 0 and the derivative of multiplication will be carried

then replace only the terms of the derivatives

l1 = a1 + b1*x + c1*y;
l2 = a2 + b2*x + c2*y;
l3 = a3 + b3*x + c3*y;

D[L1 L2, x,
NonConstants -> {L1 , L2}] /. {D[L1, x, NonConstants -> {L1, L2}] ->
D[l1, x], D[L2, x, NonConstants -> {L1, L2}] -> D[l2, x]}

This will also work with expressions such as
D[L1^2 Sin[ L2^3], x,
NonConstants -> {L1 , L2}] /. {D[L1, x, NonConstants -> {L1, L2}] ->
D[l1, x], D[L2, x, NonConstants -> {L1, L2}] -> D[l2, x]}

Try it

yehuda

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Subject (listing for 'How to calculate the partial derivative?')
Author Date Posted
How to calculate the partial derivative? tang 11/20/12 9:30pm
Re: How to calculate the partial derivative? yehuda 11/25/12 08:38am
Re: How to calculate the partial derivative? yehdua 11/25/12 08:44am
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