Error calling a function or indexing a variable, apparently the first line for plotting is wrong, can't figure out whats wrong with it...

Question

Michelle Gaughan 2020-2-23

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/507135-error-calling-a-function-or-indexing-a-variable-apparently-the-first-line-for-plotting-is-wrong-ca

编辑： Jyotsna Talluri 2020-2-26

% Plotting the error curve

error = ( (40*c) / (m*g) )-( 1-exp( (-10*c)/m ) );
g  = 9.81; % gravitational force
m  = 68.1; % mass of parachutist
h1 = figure(1);
% Create vectors
c=(0:0.5:25)
y=zeros([1 50])
% Plot the various curves
plot(c, error(c, m, g)), 'r--', 'Linewidth', 3);  
hold on;
plot(c,y,'k-', 'Linewidth', 3);
plot(5, error(5, m, g)),'.b', 'markersize', 10);
plot(c,y,'k-', 'Linewidth', 3);
xlabel('Drag coefficient c', 'fontsize', 20);
ylabel('Error', 'fontsize', 20);
title('Error as a function of c', 'fontsize', 20);
grid on;

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Answer 1

Jyotsna Talluri 2020-2-26

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https://ww2.mathworks.cn/matlabcentral/answers/507135-error-calling-a-function-or-indexing-a-variable-apparently-the-first-line-for-plotting-is-wrong-ca#answer_417383

编辑：Jyotsna Talluri 2020-2-26

error(c,m,g) is a call to the function error with input variables c,m,g .But you have not declared the error as a function ,you declared it as an expression depending on variables c,m,g .Also,the variables have to be declared before the expression.

g  = 9.81; % gravitational force 
m  = 68.1; % mass of parachutist 
error=[]; 
for c = 0:0.5:25 
  error(end+1)= ( (40*c) / (m*g) )-( 1-exp( (-10*c)/m ) ); 
end 
y=zeros([1 50]); 
h1 = figure(1); 
plot(c, error, 'r--', 'Linewidth', 3);   
hold on; 
plot(c,y,'k-', 'Linewidth', 3); 