error in gradient function for partial differential

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ahmed ashiry 2015-3-1

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/180936-error-in-gradient-function-for-partial-differential

编辑： ahmed ashiry 2015-3-1

i want the partial differential of this equation w.r.t X , Y and Z.

31.65951=sqrt((20460991.052399-X)^2+(11012393.207537-Y)^2+(13140061.841029-Z)^2)-sqrt((20462649.31-X)^2+(11012196.356-Y)^2+(13137623.266-Z)^2)

the function send to me to solve this equation was gradient but when trying it an error was happened

Use gradient

 syms X Y Z
 Eq = -31.65951 + sqrt((20460991.052399-X)^2+(11012393.207537-Y)^2+(13140061.841029-Z)^2)-sqrt((20462649.31-  X)^2+(11012196.356-Y)^2+(13137623.266-Z)^2);
 gradient(Eq)

error

syms X Y Z Eq = -31.65951 + sqrt((20460991.052399-X)^2+(11012393.207537-Y)^2+(13140061.841029-Z)^2)-sqrt((20462649.31- X)^2+(11012196.356-Y)^2+(13137623.266-Z)^2); gradient(Eq) ??? Error using ==> zeros Trailing string input must be a valid numeric class name.

Error in ==> gradient at 64 g = zeros(size(f),class(f)); % case of singleton dimension