“Unable to prove `expr` literally…” error when trying to compare a symbol inside a function
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1
down vote
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I just started learning MATLAB and I'm trying to normalize a bump function given by
function b = bump(x)
region1 = abs(x) < 1
b(region1) = (exp(-1./(1 - x(region1).^2)))
region2 = abs(x) >= 1
b(region2) = 0
end
To do this, I need to divide by the definite integral from -1 to 1. However, when I input
syms x;
int(bump(x), -1, 1)
I get a long error message, which says
Error using symengine (line 58)
Unable to prove 'abs(x) < 1' literally. To test the statement mathematically, use isAlways.
Error in sym/subsindex (line 1554)
X = find(mupadmex('symobj::logical',A.s,9)) - 1;
Error in sym>privformat (line 2357)
x = subsindex(x)+1;
Error in sym/subsref (line 1578)
[inds{k},refs{k}] = privformat(inds{k});
Error in bump (line 3)
b(region1) = (exp(-1./(1 - x(region1).^2)))
I tried replacing abs(x)<1 with what I think is the suggested isAlways(abs(x)<1), and that removes the error, although it gives the wrong answer (it says the integral is zero).
I don't understand what does the error message means.
matlab symbolic-math
edited Nov 21 at 11:27
Bebs
6413923
asked Sep 23 '13 at 18:46
Alexander Sibelius
1204
add a comment |
up vote
1
down vote
favorite
I just started learning MATLAB and I'm trying to normalize a bump function given by
function b = bump(x)
region1 = abs(x) < 1
b(region1) = (exp(-1./(1 - x(region1).^2)))
region2 = abs(x) >= 1
b(region2) = 0
end
To do this, I need to divide by the definite integral from -1 to 1. However, when I input
syms x;
int(bump(x), -1, 1)
I get a long error message, which says
Error using symengine (line 58)
Unable to prove 'abs(x) < 1' literally. To test the statement mathematically, use isAlways.
Error in sym/subsindex (line 1554)
X = find(mupadmex('symobj::logical',A.s,9)) - 1;
Error in sym>privformat (line 2357)
x = subsindex(x)+1;
Error in sym/subsref (line 1578)
[inds{k},refs{k}] = privformat(inds{k});
Error in bump (line 3)
b(region1) = (exp(-1./(1 - x(region1).^2)))
I tried replacing abs(x)<1 with what I think is the suggested isAlways(abs(x)<1), and that removes the error, although it gives the wrong answer (it says the integral is zero).
I don't understand what does the error message means.
matlab symbolic-math
edited Nov 21 at 11:27
Bebs
6413923
asked Sep 23 '13 at 18:46
Alexander Sibelius
1204
Are you using symbolic objects on purpose?
– Eitan T
Sep 23 '13 at 19:03
@EitanT: if he's just learning MATLAB, then I'd guess "no".
– nneonneo
Sep 23 '13 at 19:04
@nneonneo I'm trying not to put words in the OP's mouth, that's why I'm asking.
– Eitan T
Sep 23 '13 at 19:06
Eitan is right. My learning MATLAB consists of my Googling "matlab integrate" and seeing what comes up. So, this probably isn't what I want.
– Alexander Sibelius
Sep 23 '13 at 19:08
add a comment |
up vote
1
down vote
favorite
up vote
1
down vote
favorite
I just started learning MATLAB and I'm trying to normalize a bump function given by
function b = bump(x)
region1 = abs(x) < 1
b(region1) = (exp(-1./(1 - x(region1).^2)))
region2 = abs(x) >= 1
b(region2) = 0
end
To do this, I need to divide by the definite integral from -1 to 1. However, when I input
syms x;
int(bump(x), -1, 1)
I get a long error message, which says
Error using symengine (line 58)
Unable to prove 'abs(x) < 1' literally. To test the statement mathematically, use isAlways.
Error in sym/subsindex (line 1554)
X = find(mupadmex('symobj::logical',A.s,9)) - 1;
Error in sym>privformat (line 2357)
x = subsindex(x)+1;
Error in sym/subsref (line 1578)
[inds{k},refs{k}] = privformat(inds{k});
Error in bump (line 3)
b(region1) = (exp(-1./(1 - x(region1).^2)))
I tried replacing abs(x)<1 with what I think is the suggested isAlways(abs(x)<1), and that removes the error, although it gives the wrong answer (it says the integral is zero).
I don't understand what does the error message means.
matlab symbolic-math
edited Nov 21 at 11:27
Bebs
6413923
asked Sep 23 '13 at 18:46
Alexander Sibelius
1204
I just started learning MATLAB and I'm trying to normalize a bump function given by
function b = bump(x)
region1 = abs(x) < 1
b(region1) = (exp(-1./(1 - x(region1).^2)))
region2 = abs(x) >= 1
b(region2) = 0
end
To do this, I need to divide by the definite integral from -1 to 1. However, when I input
syms x;
int(bump(x), -1, 1)
I get a long error message, which says
Error using symengine (line 58)
Unable to prove 'abs(x) < 1' literally. To test the statement mathematically, use isAlways.
Error in sym/subsindex (line 1554)
X = find(mupadmex('symobj::logical',A.s,9)) - 1;
Error in sym>privformat (line 2357)
x = subsindex(x)+1;
Error in sym/subsref (line 1578)
[inds{k},refs{k}] = privformat(inds{k});
Error in bump (line 3)
b(region1) = (exp(-1./(1 - x(region1).^2)))
I tried replacing abs(x)<1 with what I think is the suggested isAlways(abs(x)<1), and that removes the error, although it gives the wrong answer (it says the integral is zero).
I don't understand what does the error message means.
matlab symbolic-math
matlab symbolic-math
edited Nov 21 at 11:27
Bebs
6413923
asked Sep 23 '13 at 18:46
Alexander Sibelius
1204
edited Nov 21 at 11:27
Bebs
6413923
asked Sep 23 '13 at 18:46
Alexander Sibelius
1204
edited Nov 21 at 11:27
Bebs
6413923
edited Nov 21 at 11:27
Bebs
6413923
edited Nov 21 at 11:27
Bebs
6413923
6413923
asked Sep 23 '13 at 18:46
Alexander Sibelius
1204
asked Sep 23 '13 at 18:46
Alexander Sibelius
1204
asked Sep 23 '13 at 18:46
Alexander Sibelius
1204
1204
Are you using symbolic objects on purpose?
– Eitan T
Sep 23 '13 at 19:03
@EitanT: if he's just learning MATLAB, then I'd guess "no".
– nneonneo
Sep 23 '13 at 19:04
@nneonneo I'm trying not to put words in the OP's mouth, that's why I'm asking.
– Eitan T
Sep 23 '13 at 19:06
Eitan is right. My learning MATLAB consists of my Googling "matlab integrate" and seeing what comes up. So, this probably isn't what I want.
– Alexander Sibelius
Sep 23 '13 at 19:08
add a comment |
Are you using symbolic objects on purpose?
– Eitan T
Sep 23 '13 at 19:03
@EitanT: if he's just learning MATLAB, then I'd guess "no".
– nneonneo
Sep 23 '13 at 19:04
@nneonneo I'm trying not to put words in the OP's mouth, that's why I'm asking.
– Eitan T
Sep 23 '13 at 19:06
Eitan is right. My learning MATLAB consists of my Googling "matlab integrate" and seeing what comes up. So, this probably isn't what I want.
– Alexander Sibelius
Sep 23 '13 at 19:08
Are you using symbolic objects on purpose?
– Eitan T
Sep 23 '13 at 19:03
Are you using symbolic objects on purpose?
– Eitan T
Sep 23 '13 at 19:03
@EitanT: if he's just learning MATLAB, then I'd guess "no".
– nneonneo
Sep 23 '13 at 19:04
@EitanT: if he's just learning MATLAB, then I'd guess "no".
– nneonneo
Sep 23 '13 at 19:04
@nneonneo I'm trying not to put words in the OP's mouth, that's why I'm asking.
– Eitan T
Sep 23 '13 at 19:06
@nneonneo I'm trying not to put words in the OP's mouth, that's why I'm asking.
– Eitan T
Sep 23 '13 at 19:06
Eitan is right. My learning MATLAB consists of my Googling "matlab integrate" and seeing what comes up. So, this probably isn't what I want.
– Alexander Sibelius
Sep 23 '13 at 19:08
Eitan is right. My learning MATLAB consists of my Googling "matlab integrate" and seeing what comes up. So, this probably isn't what I want.
– Alexander Sibelius
Sep 23 '13 at 19:08
add a comment |
1 Answer
1
active
oldest
votes
up vote
2
down vote
accepted
syms x defines x as a symbolic variable, invoking symbolic computation on x. This probably isn't what you want.
Instead, define x as some kind of input matrix, e.g. x = zeros(3);. Or, to do numeric integration, use the integral function:
integral(@bump, -1, 1)
answered Sep 23 '13 at 19:03
nneonneo
124k25192296
I changedxtox = -2:.01:2, but now it saysUndefined function 'int' for input arguments of type 'double'.What does this mean?
– Alexander Sibelius
Sep 23 '13 at 19:13
1
Ah. I see now. You want an integral, which requires a function. You saw the symbolic documentation first so you didn't see the numeric integration function right after that. I added an example forintegral.
– nneonneo
Sep 23 '13 at 20:03
add a comment |
1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
up vote
2
down vote
accepted
syms x defines x as a symbolic variable, invoking symbolic computation on x. This probably isn't what you want.
Instead, define x as some kind of input matrix, e.g. x = zeros(3);. Or, to do numeric integration, use the integral function:
integral(@bump, -1, 1)
answered Sep 23 '13 at 19:03
nneonneo
124k25192296
I changedxtox = -2:.01:2, but now it saysUndefined function 'int' for input arguments of type 'double'.What does this mean?
– Alexander Sibelius
Sep 23 '13 at 19:13
1
Ah. I see now. You want an integral, which requires a function. You saw the symbolic documentation first so you didn't see the numeric integration function right after that. I added an example forintegral.
– nneonneo
Sep 23 '13 at 20:03
add a comment |
up vote
2
down vote
accepted
syms x defines x as a symbolic variable, invoking symbolic computation on x. This probably isn't what you want.
Instead, define x as some kind of input matrix, e.g. x = zeros(3);. Or, to do numeric integration, use the integral function:
integral(@bump, -1, 1)
answered Sep 23 '13 at 19:03
nneonneo
124k25192296
I changedxtox = -2:.01:2, but now it saysUndefined function 'int' for input arguments of type 'double'.What does this mean?
– Alexander Sibelius
Sep 23 '13 at 19:13
1
Ah. I see now. You want an integral, which requires a function. You saw the symbolic documentation first so you didn't see the numeric integration function right after that. I added an example forintegral.
– nneonneo
Sep 23 '13 at 20:03
add a comment |
up vote
2
down vote
accepted
up vote
2
down vote
accepted
syms x defines x as a symbolic variable, invoking symbolic computation on x. This probably isn't what you want.
Instead, define x as some kind of input matrix, e.g. x = zeros(3);. Or, to do numeric integration, use the integral function:
integral(@bump, -1, 1)
answered Sep 23 '13 at 19:03
nneonneo
124k25192296
syms x defines x as a symbolic variable, invoking symbolic computation on x. This probably isn't what you want.
Instead, define x as some kind of input matrix, e.g. x = zeros(3);. Or, to do numeric integration, use the integral function:
integral(@bump, -1, 1)
answered Sep 23 '13 at 19:03
nneonneo
124k25192296
edited Sep 23 '13 at 20:02
answered Sep 23 '13 at 19:03
nneonneo
124k25192296
answered Sep 23 '13 at 19:03
nneonneo
124k25192296
answered Sep 23 '13 at 19:03
nneonneo
124k25192296
124k25192296
I changedxtox = -2:.01:2, but now it saysUndefined function 'int' for input arguments of type 'double'.What does this mean?
– Alexander Sibelius
Sep 23 '13 at 19:13
1
Ah. I see now. You want an integral, which requires a function. You saw the symbolic documentation first so you didn't see the numeric integration function right after that. I added an example forintegral.
– nneonneo
Sep 23 '13 at 20:03
add a comment |
I changedxtox = -2:.01:2, but now it saysUndefined function 'int' for input arguments of type 'double'.What does this mean?
– Alexander Sibelius
Sep 23 '13 at 19:13
1
Ah. I see now. You want an integral, which requires a function. You saw the symbolic documentation first so you didn't see the numeric integration function right after that. I added an example forintegral.
– nneonneo
Sep 23 '13 at 20:03
I changed
x to x = -2:.01:2, but now it says Undefined function 'int' for input arguments of type 'double'. What does this mean?– Alexander Sibelius
Sep 23 '13 at 19:13
I changed
x to x = -2:.01:2, but now it says Undefined function 'int' for input arguments of type 'double'. What does this mean?– Alexander Sibelius
Sep 23 '13 at 19:13
1
1
Ah. I see now. You want an integral, which requires a function. You saw the symbolic documentation first so you didn't see the numeric integration function right after that. I added an example for
integral.– nneonneo
Sep 23 '13 at 20:03
Ah. I see now. You want an integral, which requires a function. You saw the symbolic documentation first so you didn't see the numeric integration function right after that. I added an example for
integral.– nneonneo
Sep 23 '13 at 20:03
add a comment |
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Are you using symbolic objects on purpose?
– Eitan T
Sep 23 '13 at 19:03
@EitanT: if he's just learning MATLAB, then I'd guess "no".
– nneonneo
Sep 23 '13 at 19:04
@nneonneo I'm trying not to put words in the OP's mouth, that's why I'm asking.
– Eitan T
Sep 23 '13 at 19:06
Eitan is right. My learning MATLAB consists of my Googling "matlab integrate" and seeing what comes up. So, this probably isn't what I want.
– Alexander Sibelius
Sep 23 '13 at 19:08