how to overcome undefined function sum.

Question

Prabha Kumaresan 2017-12-29

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/374883-how-to-overcome-undefined-function-sum

编辑： Matt J 2017-12-29

 throughput_E =@(t)Bmax*log2(1+p_fix(t)*gamma(t)/sum(p_fix(q,1,t-1).*gamma(t)));              
 overall_throughput_E = sum(sum(throughput_E));

If i run the code i am getting Undefined function 'sum' for input arguments of type 'function_handle'.

Error in overall_throughput_E = sum(sum(throughput_E));

4 个评论
显示 2更早的评论隐藏 2更早的评论

KSSV 2017-12-29

:( what is p_fix.....show us this function.

Prabha Kumaresan 2017-12-29

p_fix is the fixed power which was given by 0.01 .

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Matt J 2017-12-29

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/374883-how-to-overcome-undefined-function-sum#answer_298052

编辑：Matt J 2017-12-29

在 MATLAB Online 中打开

You need to give some sort of input to throughput_E in this line

sum(sum( throughput_E( t_input) ));

3 个评论
显示 1更早的评论隐藏 1更早的评论

John D'Errico 2017-12-29

在 MATLAB Online 中打开

To amplify on what Matt said, and explain why there was a problem...

throughput_E is a function handle. It seems like it makes sense that you can sum the function, simply by putting it inside sum. But MATLAB does not understand your goal here. MATLAB is a very literal tool. The function sum looks at what you passed in. Sum recognizes only numeric inputs as candidates to be summable. It looks at throughput_E, and sees that it is NOT a number or vector or array of numbers. So sum just gives up and throws an error.

If you change things, so that throughput_E has an input as did Matt, then the result is now numeric. MATLAB evaluates the function at t_input, then passes the result to sum. All is good now.

Sometimes you really don't immediately have the input to throughput_E at the moment, but you want to define a new function that will take any input and sum the result, after going through throughput_E? Just create a NEW function, as I do here:

sum_of_throughput_E = @(inp) sum(sum(throughput_E(inp)));

So now you can use this new function as the summed result.

Prabha Kumaresan 2017-12-29

编辑：Walter Roberson 2017-12-29

在 MATLAB Online 中打开

i am getting the error

Undefined function or variable 't_input'

if i use sum(sum( throughput_E( t_input) ));

and if i use

sum_of_throughput_E = @(inp) sum(sum(throughput_E(inp)));

in the below coding

throughput_E = @(t)Bmax*log2(1+p_fix(t)*gamma(t)/symsum(p_fix(q,1,t-1).*gamma(t)))
% overall_throughput_E = sum(sum(throughput_E(t_input)));
overall_throughput_E = sum(sum(throughput_E));
 sum_of_throughput_E = @(inp) sum(sum(throughput_E(inp)));
%             
            output_E(t,r)=overall_throughput_E;
            output_E_it(t,r,it)=output_E(t,r);

i am getting Undefined function 'sum' for input arguments of type 'function_handle'.

Error in 
overall_throughput_E = sum(sum(throughput_E));

Please help me to solve it.

Matt J 2017-12-29

编辑：Matt J 2017-12-29

Undefined function or variable 't_input'

You must define t_input! What data are you trying to run throughput_E on?

请先登录，再进行评论。

how to overcome undefined function sum.

4 个评论
显示 2更早的评论隐藏 2更早的评论

回答（1 个）

3 个评论
显示 1更早的评论隐藏 1更早的评论

另请参阅

类别

标签

Community Treasure Hunt

how to overcome undefined function sum.

4 个评论 显示 2更早的评论隐藏 2更早的评论

回答（1 个）

3 个评论 显示 1更早的评论隐藏 1更早的评论

另请参阅

类别

标签

Community Treasure Hunt

WeChat

4 个评论
显示 2更早的评论隐藏 2更早的评论

3 个评论
显示 1更早的评论隐藏 1更早的评论