Hi People... 2 Questions Here ...

Hi Every One

1- Suppose We Have 1.7321 . Which Command returns the non-numerical value? (I mean sqrt(3) )

2-Run This

    % Interactive script to fit a cubic to data points
clf;clc;clear all;
grid on
hold on
axis([0 100 0 100]);
diff = 10;
xold = 68;
i = 0;
xp = zeros(1); % data points
yp = zeros(1);
while diff > 2
[a b] = ginput(1);
diff = abs(a - xold);
if diff > 2
i = i + 1;
xp(i) = a;
yp(i) = b;
xold = a;
plot(a, b, 'k*')
end
end
p = polyfit(xp, yp, 3 );
plotfunction=poly2sym((p))
x = 0:0.1:xp(length(xp));
y=p(1)*x.^3 + p(2)*x.^2 + p(3)*x + p(4);
plot(x,y), title( 'cubic polynomial fit'), ...
ylabel('y(x)'), xlabel('x')
hold off
  end

The Output has a large amount of number... how can i simplify it???

[Azzi Abdelmalek]

Can you explain question 1?

[Masoud Ghanbari]

I mean you have the 1.7321 and you want to radical(?)=1.7321

Answer 1

[Walter Roberson]

For #1: if you have access to the full version of Maple, such as through the old Extended Symbolic Mathematics Toolbox, then you can use the Maple command "identify". If you do have that access (it is not the current Symbolic Toolbox, which is MuPAD rather than Maple), then try

feval(symengine, 'identify', 1.7321)

or

maple(sprintf('identify(%g)', 1.7321))

MuPAD (the current Symbolic Toolbox) does not appear to have a similar function.

You could try using

simplify(plotfunction)

to get a more compact expression. The result might still have a lot of rational numbers in it. If you want the rational numbers converted to fixed point numbers, then use

vpa(plotfunction)

[Masoud Ghanbari]

Dear Walter .. Thanks For the vpa... It Worked

the first answer failed

Run this and tell me why elseif does not work , Please

 %  
clf;clc;clear all;
grid on
hold on
axis([0 100 0 100]);
diff = 10;
xold = 68;
i = 0;
xp = zeros(1); % data points
yp = zeros(1);
while diff > 2
[a b] = ginput(1);
diff = abs(a - xold);
if diff > 2
i = i + 1;
xp(i) = a;
yp(i) = b;
xold = a;
plot(a, b, 'k*')
end
end
p = polyfit(xp, yp, 3 );
plotfunction=poly2sym((p));
fitfunction = vpa(plotfunction,4)
x = 0:0.1:xp(length(xp));
y=p(1)*x.^3 + p(2)*x.^2 + p(3)*x + p(4);
plot(x,y), title( 'cubic polynomial fit'), ...
ylabel('y(x)'), xlabel('x')
hold off

 userans=input('Do You Want The Result With More Precision? (Y/N)\n','s');
if userans == 'Y' || 'y' 
clc;
plotfunction =poly2sym((p));
fitfunction
fullfitfunction = plotfunction
msgbox('Done');
elseif userans == 'N' || 'n'
msgbox('Done');
mghanbari.ir </a>')

 end

end

if you type 'n' it will do the same as when you type 'y'

[Walter Roberson]

The line

if userans == 'Y' || 'y'

means the same thing as

if ((userans == 'Y') || ('y'))

which means the same thing as

if ((userans == 'Y') || ('y' ~= 0))

And since 'y' is indeed non-zero, the test is always true.

[Masoud Ghanbari]

The What is the correct format?

[Jan]

if strcmpi(userans, 'y')

[Masoud Ghanbari]

Thanks Dear Friends...