This is how I would do it:
Integrating the quadratic without integration limits and displaying the result:
prompt = {'x^2 Coefficient', 'x Coefficient', 'Constant'};
default_ans = {'0','0','0'};
dlg_title = 'Quadratic Equation';
num_lines = 1;
valc = inputdlg(prompt, dlg_title, num_lines, default_ans);
vals = cell2mat(valc);
valn = str2num(vals);
qcf = valn(1:3);
qint = polyint(qcf.');
CreateStruct.Interpreter = 'tex';
CreateStruct.WindowStyle = 'modal';
msgbox(sprintf('Integral of: \n%.2f\\cdotx^2 %+.2f\\cdotx %+.2f = \n%.2f\\cdotx^3 %+.2f\\cdotx^2 %+.2f\\cdotx %+.2f', [qcf.' qint]),'Value',CreateStruct)
Integrating the quadratic with limits and displaying the results of the integration:
prompt = {'x^2 Coefficient', 'x Coefficient', 'Constant', 'Lower Integration Limit','Upper Integration Limit'};
default_ans = {'0','0','0','0','0'};
dlg_title = 'Quadratic Equation';
num_lines = 1;
valc = inputdlg(prompt, dlg_title, num_lines, default_ans);
vals = cell2mat(valc);
valn = str2num(vals);
qcf = valn(1:3);
int_lim = valn(4:5);
qint = polyint(qcf.');
int_val = diff(polyval(qint, [int_lim(1),int_lim(2)]));
CreateStruct.Interpreter = 'tex';
CreateStruct.WindowStyle = 'modal';
msgbox(sprintf('Integral of %.2f\\cdotx^2 %+.2f\\cdotx %+.2f from %.2f to %.2f = %.3f', [qcf.' int_lim.' int_val]),'Value',CreateStruct)
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EDIT — Added the integration without limits.
