Mathematics Upgrade Issues :: (MATLAB Release Notes)

MATLAB Release Notes

Mathematics Upgrade Issues

The issues involved in upgrading from MATLAB 6.5 to MATLAB 7.0, in terms of mathematics features, are discussed in the following sections:

Integer Data Type Functions Now Round Instead of Truncate

The following integer data functions now round noninteger inputs instead of truncating:

int8
uint8
int16
uint16
in32
uint32
int64
uint64

For example,

```
int8(3.7) 
```

returns

```
ans =

    4
```

in MATLAB 7.0. In previous releases, the same command returned 3. If you have code that contains these functions, it might return different results in Version 7.0 than in previous releases, in particular, results that differ by 1 after converting floating-point inputs to an integer data type.

You can turn the following warning on to help diagnose these differences:

```
warning on MATLAB:intCovertNonIntVal
```

See New Warnings for Integer Arithmetic for more information about this and other new warning messages.

max and min Now Have Restrictions on Inputs of Different Data Types

In MATLAB 7.0, the functions max and min now have the following restrictions on inputs of different data types:

If any input has an integer data type, all other inputs must have the same integer data type or type scalar double.
If any input is of type single, all other inputs must have type double or single.

Other combinations of inputs now return an error message. In previous releases, inputs to max or min could have any combination of data types.

For the allowed mixed-type combinations listed above, max and min now return results of a different data type than in previous releases.

If one input has an integer data type, while another has type double, the result now has the same integer data type. In previous releases, the result had type double.
If one input has type single, while another has type double, the result now has type single. In previous releases, the result had type double.

You can turn on the following warning messages to diagnose any issues that might result from this change in behavior:

warning on MATLAB:max:mixedIntegersScalarDoubleInputs
warning on MATLAB:max:mixedSingleDoubleInputs
warning on MATLAB:min:mixedIntegersScalarDoubleInputs
warning on MATLAB:min:mixedSingleDoubleInputs

Changes to Behavior of Concatenation

When you perform concatenation ([a, b], [a;b], and cat(a,b,dim)) on mixed integer and other numeric or logical inputs, the left-most integer type among the inputs is the type of the result. As a result, the other inputs might lose values when they are converted to the integer data type. In Version 7.0, MATLAB now returns a warning when you concatenate these mixed data types.

For example,

[int8(100) uint8(200)]
Warning: Concatenation with dominant (left-most) integer class 
may overflow other operands on conversion to return class.
(Type "warning off MATLAB:concatenation:integerInteraction" to 
suppress this warning.)

ans =

  100  127

class(ans)

ans =

int8

Concatenating an input of any nondouble numeric data type (single and integer data type) with type char now returns a result of type char. In previous releases, the same operation returned a result of the same type as the numeric data type.

Changes to the Behavior of Sum

In Version 7.0, sum applied to a vector of type single performs single accumulation and returns a result of type single. In previous releases, sum performed this operation in double accumulation. To restore the previous behavior, call sum with the syntax

```
sum(X, 'double')
```

```
sum(X, dim, 'double')
```

See New Class Inputs for sum for more information on this new syntax.

FFT Functions Applied to Integer Data Types are Becoming Obsolete

In previous releases, the following fast Fourier transform (FFT) and related functions cast integer inputs of type uint8 and uint16 to double, used the double algorithm, and returned a double result:

fft
fftn
ifft
ifftn
conv2

In Version 7.0, these operations return warning messages that recommend convert the inputs to double before applying the function, for example, by fft(double(x)).

New Warnings for Complex Inputs to atan2, log2, and pow2

The following functions now return a warning for inputs that are not real numbers:

atan2(y,x)
[f,e] = log2(x)
pow2(f,e)

New Names for Demos expm1, expm2, and expm3

The demos expm1, expm2, and expm3 have been renamed expmdemo1, expmdemo2, and expmdemo3, to avoid a name conflict with the new function expm1.

Matrix, Trigonometric, and Other Math Functions No Longer Accept Inputs of Type char

Matrix functions, such as chol, lu, and svd, and trigonometric functions, such as sin and cos, no longer accept inputs of type char. In previous releases, these functions simply converted char inputs to double before performing operations on them. To restore the previous behavior of these functions, create an M-file that converts its input to double before applying the function. For example, to restore the behavior of sin,

Create a directory called @char in a directory on the MATLAB path, for example, your work directory.
Create an M-file with the following commands:

function s = sin(x)
s = sin(double(x));

Save the file as sin.m in the directory @char.

Colon Operator on char Now Returns a char

Applying the colon operator to inputs of type char now returns a result of type char. For example,

```
'a':'g'

ans =

abcdefg
```

In previous releases, the same operation returned a result of type double.

Obsolete Functions

The functions listed in the left column of the following table are obsolete and will be removed from a future version of MATLAB. Use the replacement functions listed in the right column instead.

Obsolete Function
Replacement Function

colmmd
colamd

quad8
quadl

symmmd
symamd

Obsolete Function	Replacement Function
`colmmd`	`colamd`
`quad8`	`quadl`
`symmmd`	`symamd`

The following obsolete functions are no longer included in MATLAB:

fmin
fmins
icubic
interp4
interp5
interp6
meshdom
nnls
saxis

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